Domtrapphuset, Stone building in Fjärdingen, Uppsala, Sweden

Domtrapphuset is a stone building three to four storeys high, with a rust-brown plastered facade and grey-green joinery. Its central three-storey tower carries a sheet-metal roof topped by the cupola it received during the 1764–1767 restoration. It stands by the cathedral cemetery wall in Fjärdingen and today holds flats, institutional rooms and a basement restaurant.

Domtrapphuset is first mentioned in writing in 1376 and was probably built around 1280, though some date it to the 1330s; it is considered Uppsala's oldest surviving building. In 1460 the cathedral exchanged the stone house by the eastern cemetery stair to canon Henrik Lang, who returned it to the cathedral chapter in 1472. Gustav Vasa confiscated it at the Reformation and gave it to Per Brahe the Elder in 1548. Badly damaged in the 1702 town fire, it was repaired 1764–1767 to drawings by Carl Johan Cronstedt, when the tower gained its dome.

From the 1790s until they built their own houses in the late 19th century, several student nations rented rooms here, among them Norrlands nation, Södermanlands-Nerikes nation, Gästrike-Hälsinge nation and Kalmar nation. Katedralskolan also held its premises in the house during the 18th century. Since the 1930s the building has housed restaurants, and today Restaurang Domtrappkällaren occupies the cellar.

The building is still in use as housing and institutional premises, and since the 1930s it has housed restaurants; today Restaurang Domtrappkällaren occupies the cellar. The restaurant entrance is in the basement, reached from the cathedral square side, so look for the lower door rather than the main house door. The upper floors are not open to visitors.

In the 18th century a cellar room in the stone house served as a prison for Uppsala students guilty of minor disciplinary offences, or as a debtors' cell for those who could not pay. The student prison, called "Prubban" from Latin "proba", was formally abolished in 1852.