The Strasbourg astronomical clock is located in the Cathédrale Notre-Dame of Strasbourg, Alsace, France. It is the third clock to make its home there and was built at the time of the first French possession of the city (1681–1870). The first clock had been built in the 14th century, the second in the 16th century, when Strasbourg was a Free imperial city of the Holy Roman Empire.
The current, third clock dates from 1843. Its main features are a perpetual calendar (including a computus), an orrery (planetary dial), a display of the real position of the Sun
and the Moon, and solar and lunar eclipses. The main attraction is the procession of the life-size figures of Christ and the Apostles which occurs every day at 12:30pm, that is at noon clock time. The walkabout also occurs at midnight clock time.
The second clock stopped working around 1788 and stood still until 1838, when Jean-Baptiste Schwilgué (1776–1856) started to build the current clock. He designed new mechanisms to replace the old ones and which were meant to be state of the art. Schwilgué had wanted to work on the clock since his boyhood, but he only got the contract 50 years later. In the meantime, he had become acquainted with clockmaking, mathematics, and mechanics. He spent one year preparing his 30 workers before actually starting construction. Then, construction lasted from 1838 until June 24, 1843. The clock, however, was inaugurated on December 31, 1842.
This clock contains the first perpetual mechanical Gregorian computus, designed by Schwilgué in 1816.