Altes Rathaus, Medieval town hall at Altmarkt, Cottbus, Germany.

Altes Rathaus was a three-storey plastered brick building on the Altmarkt in Cottbus, aligned north-south with seven axes and topped by a mansard hip roof with an octagonal roof turret, lantern and onion dome. A six-axis extension joined it at right angles, featuring a pointed-arch portal, external staircase and stepped gable; its lower storey was rusticated with quoins.

The oldest part of the Altes Rathaus was built in the late 14th century on the Altmarkt, along with the Ratskeller. A lightning strike destroyed the tower in 1542; it was rebuilt by 1545. After a city fire in March 1671 reduced the building to its foundations, reconstruction was completed in 1690. A new town hall was inaugurated on the Neumarkt in December 1937, after which the old building housed the traffic office, city treasury and tax office. It burned down on 21 April 1945 and the ruin was demolished in 1948.

The Ratskeller, created with the oldest part of the town hall in the late 14th century, was the only place in Cottbus where beer brewed outside the city could be served. The town ran it until the 17th century as an important source of income, after which it was leased out. It was reopened on 13 July 1895 after renovation.

The Altes Rathaus no longer exists: it burned down on 21 April 1945 and its ruins were demolished in 1948. Its site is the Altmarkt in central Cottbus, about 170 metres east of the current town hall on Neumarkt. Nothing of the building remains to visit, so look for the square itself and the later town hall as the reference points.

During World War I, residents were invited to hammer nails into a special door of the building as part of a fundraising campaign. This creative method helped the community raise money during wartime financial hardship.