This town hall dates from 1225,and is probably the oldest in the Netherlands. The quadrangular floorplan and volume with corner towers looks very similar to that of the Leuven town hall,that is about two centuries younger.
It was built in ledestone.
The high understructure still recalls the defensive function.
The back facade has an early gothic profile, with a stepped gable. The windows of the ground floor are omanesque, with ate romanesque arches with diving columns. The round turrets accentuate the square form of the building ,and make the building more slender.
When the town was devastated 1380 by the people of Ghent under Lodewijk van Male, the aldermen's house partially burnt down. Only the east facade was saved. In 1407 the front- and side facade along the Grote Markt were rebuilt. The square belfry tower itself was built in 1460 and contains the carillon. The tower is crowned with a beautiful wallwalk with an octogonal bell chamber on top. The two half raised statues on the facade of the bell tower represent the counts of Flanders and Aalst.
the sundial between the two statues was originally as old as the bell tower . In 1600 the new sundial was placed and 80 years later it was regilded by Jan Lipperry.
The inscription 'NEC SPE, NEC METU'('not out of hope, not out of fear') on the facade was the motto of Philips II, earl of Aalst (1555).
The little chapel on the Grote Markt dates from the end of the 15th century and has beautiful late gothic vaults.
During the night of the Aalst-fair on 7 july 1879 part of the old aldermen's house burnt down again. The damage was considerable. The baroque crowning of the facade, the fronton and the little tower were replaced by a gothic construction. The restauration started with the tower of the bell tower, but the sundials were not replaced. The reconstruction of the facade was realised in 1886.