The Old Town Hall houses the Municipal Museum. General reconstruction of the Town Hall on the occasion of the Museum's centenary (1968) was very important for discovering the oldest shapes of the building. Several finds have been made accessible to public following the reconstruction e.g. part of the Gothic chapel, two facades facing the courtyard.
In 1387 the City Council bought half of Jacob's house to establish the town hall in it. It was not a common burgher house but a larger building where the City Council had already held its sessions. The house originated on the basis of a fortified yard with a tower from the second half of the 13th century. In 1421 the town managed to buy also the second part of the house and the new town hall complex formed a large block. On its sides streets ran from the main square to the market place behind the town hall. A year later (1422) rich burgher Hans Pawer gained the southern street and had a house with remarkable facade built there. The new facade had four high windows on the first floor, in front ot which there was a protruding gable in form of a walled grille. That house was joined to the town hall in 1430-1434. From the 1st half of the 15th century several town hall rooms were made use of. Apart from a mint in the courtyard there was a jail in the rear part of the building. In 1439 a new Council Hall with new painted wall paper was opened, in 1443 the Chapel on the tower. The Town Hall's reconstruction of 1457 is of greatest significance as it resulted in a new passageway segmented entrance portal and ribbed vault with figural brackets. At that time a new chapel was built with ribbed vault and beautiful windows. In the Chapel are pictures presenting scenes from Christ's life, figures of holy men and a coat-of-arms complemented by painted ornaments. Mural paintings of the same type as those in the green room were made in the Council Hall. The new facade consisted of a white net and red frames around the windows. The reconstructed Town Hall complied with social and artistic demands of the period till the end of the 15th century when its facade was unified by minor windows and a bay was built above the entrance, reminding people of the bay in the Castle Palace. Also its roof was changed into the form we know now. The large attic was illuminated by three stone windows in the dormers made by stonemason Pavol Plemel. The Town Hall tower had a high roof with gallery and corner bays. At the end of the Middle Ages Bratislava Town Hall had several rooms for representation and practical needs of the City Council. Medieval find prove the eventful development of the oldest preserved town hall in Slovakia.
During the last completion of the Town Hall in 1912 according to the designs by a Budapest architect J. Hbner the roofs of the buildings were unified by special glazed ceramic roofing. The roof leading to Primacilne Square consisted of green slates with a geometric pattern from brown and ochre ones. The roof of the yard wing was covered with brown slates. The glazed slates were made by Zsolnay's ceramic factory in Pécs. In the 1980s the roof was in a very bad condition. During various reconstructions part of the original roofing was substituted by news slates made from modern materials. In 1988 the roofing supplies represented the greatest problem in the roof renovation. Ceramic works in Breclav-Postorn was considered, as that provided restoration of the roof of St Stephen's Cathedral in Vienna after World War II and repair of the roof of St Elizabeth's Cathedral in Kosice. However, in the days when the roof repair was being prepared the traditional production stopped in Breclav. A contract was made with the firm Verticum - Verticlean in Budapest, which provided the production of roofing in the factory in Pécs, where the slates were made according to the original technology (original colours, hand glazing). The roofing samples were tested in the State Testing Office. According to the results of testing, the roofing's service life will surpass 50 years guaranteed by the manufacturer.
The unique door with fourteen locks in the Old Town Hall ranks among significant artefacts of smiths's art from the period of Renaissance in Bratislava. It was made during the Town' Hall's reconstruction about 1570. Then the City Council began to use the room in the tower as treasury. It was to be accessible through a door which should have been so massive and technically complicated as to be able to be inaccessible and at the same time to be artistically impressive and contribute to the Town Hall's representative character. The door is richly decorated with Renaissance ornaments, spirals, volutes, mascarons. The technical mechanism reminds us of that of a chest. The door has a three lock lock which starts the operation of the whole intricate lock mechanism on the door edge. The lock is protected by a capsule which opens by a specific code by means of movable hands. Today the door represents part of the Museum exhibition.