Every hour, hundreds of visitors gather in front of Prague’s Old Town Hall. They look upwards, waiting for a skeleton to ring a bell, two small doors to open and the Twelve Apostles to appear.
The performance lasts less than a minute. Yet the Prague Astronomical Clock, known in Czech as the Pražský orloj, is far more than an elaborate medieval show. Its astronomical dial presents a symbolic model of the universe, while its moving figures remind spectators about the passage of time and the inevitability of death.
Installed in 1410, it is one of the oldest astronomical clocks in the world and the oldest one that is still operating.
Where Is the Prague Astronomical Clock?
The Astronomical Clock is mounted on the southern wall of the Old Town Hall in Old Town Square.
The Old Town Hall was established in 1338, after King John of Luxembourg granted the citizens of Prague’s Old Town permission to create their own municipal administration. The complex gradually expanded as neighbouring houses were purchased and connected.
The clock was installed on the side of the tower facing the square. This allowed the inhabitants of medieval Prague to see the time, observe astronomical information and follow the religious calendar.
Today, the clock is one of the highlights of our Old Town and Jewish Quarter Free Walking Tour. We stop here to explain how this extraordinary medieval clock works, uncover the meaning behind its mysterious symbols, and share some of the fascinating legends that have grown around it over the centuries.
Who Built the Prague Astronomical Clock?
The oldest part of the clock was created in 1410 by Mikuláš of Kadaň, a clockmaker who worked for the royal court.
He collaborated with Jan Šindel, an astronomer, mathematician and professor at Prague University. Šindel probably provided the astronomical calculations, while Mikuláš constructed the mechanism.
This makes the Astronomical Clock a product of both scientific knowledge and exceptional craftsmanship. Its creators had to translate complex observations of the sky into a mechanical system of wheels, gears and moving indicators.
The clock did not originally look exactly as it does today. Different elements were added, repaired or replaced over the following centuries.
Was the Clock Built by Master Hanuš?
Many visitors are told that the Astronomical Clock was created by Master Hanuš. This is one of Prague’s most famous legends, but it is not historically accurate.
Master Hanuš, whose real name was Jan Růže, worked on the clock at the end of the fifteenth century. He may have repaired or improved the mechanism, but surviving documents show that its oldest astronomical section had already existed since 1410.
The incorrect attribution became widely accepted partly because later generations had forgotten the names of Mikuláš of Kadaň and Jan Šindel. The legend of Master Hanuš eventually became more famous than the documented history of the clock.
The Astronomical Dial
The upper dial is the oldest and most complicated part of the clock. It does not simply show the hour. It presents several systems of measuring time and illustrates the movement of the Sun and Moon through the sky.
To understand it, imagine that you are looking at a medieval representation of the universe.
Earth occupies the centre. Around it move the Sun, Moon and zodiac. This reflects the geocentric understanding of the cosmos that was common in medieval Europe.
The dial was not designed as a modern scientific diagram. It combines astronomical observation with symbolism and medieval ideas about the structure of the universe.
The Colours of the Sky
The background of the astronomical dial is divided into several coloured sections.
The blue area represents the part of the sky visible above Prague during the day. The darker sections represent sunrise, sunset and the periods of twilight.
The black section at the bottom represents night, when the Sun has moved below the horizon.
Latin words around the dial identify different parts of the day:
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Aurora means dawn.
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Ortus means sunrise.
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Occasus means sunset.
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Crepusculum means twilight.
The position of the golden Sun shows whether it is daytime, nighttime or one of the transitional periods between them.
The Golden Sun
The golden Sun moves across the astronomical dial throughout the year.
Its position indicates the time of day, but it also shows the Sun’s location in the zodiac and its changing height above the horizon. Because the length of daylight changes during the year, the Sun follows a different path in summer than in winter.
A golden hand connected to the Sun points towards several sets of numbers. These allow the clock to display different methods of measuring time.
The Moon
The clock also shows the movement and phases of the Moon.
A small sphere, coloured partly black and partly silver, rotates as it travels around the dial. Its appearance changes automatically to represent the current lunar phase.
This is one of the clock’s most impressive mechanical details. Without modern electronics, the mechanism can indicate whether the Moon is new, full or somewhere between the two.
The Zodiac Ring
The inner circle carries the twelve signs of the zodiac.
The ring represents the ecliptic, the apparent path followed by the Sun through the sky during the year. It is placed at an angle and moves slightly because of the way the sky was understood and represented from Prague’s geographical position.
The zodiac was important not only for astronomy. In medieval Europe it was also connected with medicine, agriculture, astrology and the religious calendar.
How Many Different Times Does the Clock Show?
The astronomical dial displays several ways of measuring time.
Central European Time
The golden hand points towards Roman numerals that show Central European Time, making this the easiest time scale for a modern visitor to recognise. There is one important difference: the astronomical clock does not adjust for daylight saving time, so during the summer months it shows one hour less than the time on our watches and phones.
Old Czech Time
The outer ring displays golden Gothic numbers.
This system counts the hours from sunset. The twenty fourth hour therefore always coincides with sunset, regardless of the season.
Because sunset occurs at a different time every day, the outer ring must move during the year.
Babylonian Time
The curved lines across the blue part of the dial divide the period between sunrise and sunset into twelve parts.
These hours are not always equal in length. A daylight hour is longer in summer, when the days are long, and shorter in winter.
Also known as unequal or planetary hours, this system is one of the clock's most unusual features. The Prague Astronomical Clock is considered unique among surviving historical astronomical clocks in its ability to display these hours mechanically.
Sidereal Time
The clock can also indicate sidereal time, which is based on the apparent movement of the stars rather than the Sun.
This was especially useful for astronomical observation.
The Calendar Dial
Below the astronomical clock is a large calendar dial.
The current design is based on a calendar plate created by the Czech painter Josef Mánes in 1866. Because the original was exposed to the weather and gradually deteriorated, the dial visible outside is a copy. The original is preserved by the Prague City Museum.
At the centre of the calendar is the coat of arms of Prague’s Old Town. Around it are twelve medallions representing the months of the year.
Instead of using only abstract symbols, Mánes depicted scenes from rural life. People work in the fields, gather crops and perform seasonal activities. The paintings create an idealised picture of the traditional agricultural year.
Smaller medallions contain the signs of the zodiac. The outer section lists the days of the year, saints’ feast days and other calendar information.
The Moving Figures
Four figures stand beside the astronomical dial. Each one represents a human fear or moral weakness.
Vanity
A man looking into a mirror represents vanity and excessive concern with physical appearance.
Greed
A figure holding a bag of money represents greed and miserliness. It is sometimes incorrectly described as a stereotypical medieval moneylender.
Death
A skeleton represents Death. It rings a bell and turns an hourglass, reminding everyone that time is passing and that no one can escape mortality.
The Turk
The fourth figure is traditionally known as the Turk. Interpretations of its meaning vary. It has been associated with pleasure, luxury or threats from beyond Christian Europe, reflecting the fears and stereotypes of the period in which the figure was created.
During the hourly performance, Death rings the bell while the other figures move their heads, as if refusing to accept that their time has come.
The Walk of the Apostles
When the clock strikes the hour, two small windows above the astronomical dial open.
Figures of the Twelve Apostles pass slowly behind the openings. Each Apostle carries an object traditionally connected with his identity.
The procession is much younger than the astronomical mechanism. Moving religious figures were probably added in an early form during the seventeenth or eighteenth century. The current statues were created after the originals were destroyed in 1945.
After the Apostles have passed, a golden rooster moves and crows. The clock then strikes the hour.
The entire performance is short, which sometimes surprises visitors who have waited a long time to see it. The real importance of the clock, however, lies in the complexity of its mechanism and the symbolism of its dials.
The Legend of Master Hanuš
According to the best known legend, Prague’s councillors commissioned Master Hanuš to build the clock.
When they saw the completed masterpiece, they became afraid that he might create an even more impressive clock for another city. They therefore sent men to his home and had him blinded.
Master Hanuš eventually discovered who had ordered the attack. With the help of an assistant, he entered the clock tower and placed his hand inside the mechanism. The machinery crushed his hand, but the clock stopped.
The legend claims that nobody was able to repair it for many years.
The story is dramatic, but there is no reliable evidence that the councillors blinded Master Hanuš or that he deliberately damaged the clock. It belongs to a wider European tradition of legends about artists punished to prevent them from repeating their masterpieces.
The Curse of the Astronomical Clock
Another legend claims that Prague will suffer if the clock is neglected or allowed to stop.
Some versions say that the skeleton will nod its head in confirmation shortly before disaster strikes. The only person capable of preventing the catastrophe is supposedly a boy born on New Year’s night.
The legend reflects the importance of the clock to the city. For generations of Prague residents, its continued movement symbolised order, stability and the survival of the Old Town.
In reality, the clock has stopped many times because of mechanical problems, repairs and historical events. Prague has always survived.
Repairs and Reconstructions
Maintaining such a complicated mechanism has never been easy.
In 1552, Jan Táborský of Klokotská Hora carried out an important repair and wrote a detailed description of the clock. His work became one of the most important historical sources about its construction and operation.
Further repairs followed during the seventeenth, eighteenth and nineteenth centuries. At several points, the mechanism was in such poor condition that municipal officials considered removing it.
A major restoration was completed in 1866. The clock received the calendar plate designed by Josef Mánes, while its mechanism was repaired and modernised.
The Destruction of 1945
The most serious damage occurred during the Prague Uprising at the end of the Second World War.
On 8 May 1945, German forces fired on the Old Town Hall. The building caught fire, and parts of the Astronomical Clock were badly damaged. The wooden figures of the Apostles were destroyed, and the calendar dial suffered significant harm.
The eastern wing of the Old Town Hall was also destroyed and was never rebuilt. The open space beside the tower still marks where this part of the building once stood.
Despite the damage, Czech clockmakers and restorers managed to repair the mechanism. The clock returned to operation in 1948, with a new set of Apostles created by sculptor Vojtěch Sucharda.
Its restoration became a symbol of Prague’s recovery after the war.
Is the Astronomical Clock Original?
The clock contains elements from many different periods.
Its astronomical mechanism and dial preserve the basic principles of the system created in 1410. Other parts, including the calendar plate, statues and decorative details, have been repaired or replaced over the centuries.
It is therefore not an untouched medieval object. It is a living historical monument that has developed together with Prague.
Each generation has repaired it using the knowledge, materials and artistic preferences of its own time. Its authenticity lies not only in the age of individual components, but also in the continuity of its function.
Can You Visit the Interior?
Visitors can enter the Old Town Hall and climb or take a lift to the top of its tower. The viewing gallery offers one of the best panoramas of Old Town Square and the historic centre of Prague.
A guided visit to the Old Town Hall may also include the medieval underground rooms, historical halls and a closer look at the interior of the Astronomical Clock.
From inside the tower, you can see the Apostles waiting behind the two small windows. The figures appear surprisingly simple when viewed from behind, as they were designed to be seen briefly from the square below.
When Should You See the Clock?
The procession of the Apostles usually takes place every hour during the day.
The area directly in front of the clock becomes extremely crowded shortly before the performance. Arriving several minutes early gives you a better chance of seeing the windows and moving figures.
Be particularly careful with your belongings. The dense crowd creates good conditions for pickpockets.
If you want to examine the astronomical dial itself, come early in the morning or later in the evening. The clock is beautifully illuminated after dark, and Old Town Square is usually calmer once the largest tour groups have left.
More Than a Tourist Attraction
The Prague Astronomical Clock is often treated as a short spectacle, but its real story is much richer.
It is a medieval model of the cosmos, a public calendar, a mechanical work of art and a reminder that every human life is limited by time. Its history also reflects the history of Prague itself, including periods of prosperity, neglect, war and reconstruction.
Once you understand the meaning of its colours, circles and moving figures, the clock no longer appears to be a confusing collection of decorations. It becomes what its creators intended: a miniature universe moving on the wall of the Old Town Hall.
You can discover the Astronomical Clock and many other landmarks of Prague’s historic centre on our Old Town and Jewish Quarter Free Walking Tour. We explore Old Town Square, explain the clock’s most fascinating details and continue through the medieval streets of the Old Town and the former Jewish Quarter.
Article by: Michal, licensed Prague guide and founder of Free Walking Tour Prague.