The building was constructed at the turn of the 15th and 16th centuries right in front of the cathedral tower in an alley off Cathedral Square. A city wall was used for its construction: the house was added to the defensive wall. It is likely that the house was bought and rebuilt by the Mikołajowski family. The interior of the house contains elements from the turn of the 15th and 16th centuries.
For example, the original Renaissance stonework of the window openings and sgraffito decoration (layered wall painting) are characteristic of the period.
The building has many original architectural details, the most interesting being the portals – the entrance and two inside the building, as well as the outside and inside plaques.

The first of the carved stone portals, with the Kościesza coat of arms in the lintel, can be found at the main entrance. This coat of arms raises questions about the time of the construction of the building. According to the inscriptions on the shields of the coat-of-arms in the interior and on the front elevation, the house was built in 1524 by Jan Mikołajowski of the Gryf coat of arms. However, according to information from 1527, the Mikołajowski House was formerly called 'Kornuszowski', and the Kościesza coat of arms at the entrance portal is not associated with the Mikołajowski family.

The next two carved portals are in the vestibule on the ground floor – one ending in an ogee arch and the other in the form of a truncated trefoil arch. The next portals on the first floor are of the Wawel type, attributed to Benedykt from Sandomierz. The last Renaissance portal is located in the passage to the next tenement.

From 1930 onwards, the tenement housed the Municipal Health Centre and the Hygiene Museum.
The gallery of the Diocesan Museum houses the oldest Passion cycle in Polish panel painting – eight Passion scenes composed on the backs of the wings of a triptych from Ptaszkowa from the years 1430–1440.