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Classroom lesson · Prague Astronomical Clock · 🇨🇿 Czechia

Prague Astronomical Clock

A 600-year-old clock that puts on a show every hour

The ornate Prague Astronomical Clock on the Old Town Hall tower

Photo · Wikimedia Commons

What is it?

In the middle of Prague, on the wall of the Old Town Hall, there is a clock unlike any other. It is called the Orloj and it is more than 600 years old. Every hour, tiny carved figures parade across the clock face while bells ring — and crowds of visitors stop and look up in wonder.

Tell me more

The Orloj was built in 1410, which means it was already old when Columbus sailed to America. That makes it one of the oldest working astronomical clocks in the whole world. It is still ticking today, doing the same job it was built for centuries ago.

The clock has two main round dials. The upper one shows the position of the Sun and Moon in the sky, which is what 'astronomical' means — it is tracking the movements of things in space. The lower dial is a beautiful calendar wheel, painted with pictures of the twelve months of the year.

Every hour on the hour, wooden figures appear from small doors above the clock. Twelve Apostles (important figures from Christian tradition) parade past the windows one by one. A golden cockerel flaps its wings and crows at the end. Visitors below in the square have been watching this show for hundreds of years.

The clock face is decorated in deep blue, gold and red, and is covered in symbols that medieval craftsmen used to explain time. Reading it is like cracking a secret code. Astronomers and clock-makers still visit Prague just to study how it works.

In the classroom

Walk your class through this in 15 minutes.

Talk together

Discussion prompts

  1. 01How do you think people knew what time it was before clocks were invented?
  2. 02Why do you think crowds still gather to watch the Orloj every hour, even though they know exactly what will happen?
  3. 03What would you put on a clock face to show something important about your town?
Try this

Classroom activity

Design your own clock face on A4 paper. Instead of just numbers, draw twelve pictures — one for each month of the year — going around the outside, just like the Orloj's calendar wheel. What picture best represents each month where you live?

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