Ulm's Rathaus is one of the most elaborately decorated civic buildings in southern Germany. Built in 1370 as a trading house and converted to town hall use in 1419, the building's most striking feature is its painted facade: an elaborate programme of murals depicting the virtues, vices, and commandments, plus an astronomical clock installed on the east gable in 1520. The clock still works and shows the phases of the moon, the position of the sun, and other celestial data alongside the time.
The building is located on the Marktplatz, right beside the Minster. The exterior is the thing to see: the interior is used for municipal functions and not generally accessible to visitors. The east facade with its clock and the golden details of the astronomical instruments are the most photographed parts. The Marktplatz also hosts a regular weekly market which brings the square to life on Saturday mornings.