Description from the City of Delft web site.

"Since the 13th century the Count of Holland owned a court on the site of the present town hall. About 1435 the court with the buildings and the market field (that till then also belonged to this count) became part of the town Delft. Parts of the complex were repaired and adapted for its new function as town hall. The former town hall of Delft was situated near the corner Choorstraat-Voorstraat. The various expansions and repair activities resulted in a cluster of buildings of which the former 13th century prison-tower, which originally had been a part of the count´s court, is the most prominent. In the 13th century, when Delft was considerably smaller than the present towncentre, Delft had almost exclusively wooden buildings. The church, built about 1200 at the location of the present Oude Kerk, was built in tuff and probably the only stone building in the town. Halfway the 13th century the count´s court was furnished with a brick tower, which was used as prison. In those days it was rather unusual to built in brick (in Dutch, brick and stone both means: ´steen´) and therefore the tower was called ´Het Steen´. At the end of the 13th century, west of it, a larger prioson-tower was built, also in brick. Since then the oldest tower was called ´Het Oude Steen´ and the new one ´Het nieuwe Steen´. In the 15th century both towers became part of the town hall, which in the course of time was enlarged and modernized. During the great fire in 1536 the town hall burnt down. It was restored, slightly modernized and enlarged in the course of the 16th century. In the 15th century, when the tower became part of the town hall, ´Het Nieuwe Steen´ was raised with a stone storey, which had a gallery at the bottom. This was the stand for the town-crier and the watchman who was looking out for possible troubles, for instance besiegers or fires. The raised part of the tower was furnished with bells, a clockwork and a carillon. In the older basement was a cellar, a room on the ground-floor for special occasions, probably the council-chamber, and at the storeys were prison-cells. A stone staircase-turret was erected at the outside against the back wall, in order to create more space inside and to give good access to the first floor of the northern wing. The small gate at the back, through which the staircase is now accessible, was fitted in 1618. Right of it we can still trace a bricked up window gab, which, like the low gate next to it, probably originates from the 16th century. The exterior of the tower has been kept almost undamaged, except for the gallery, which was harshly restored about 1850. In one of the tower rooms a wooden lockup survived the restorations. It is set up as a small museum called: ´Het Steen´, in which various instruments of torture are put together. The town hall burnt down completely in 1618. Only the tower, ´Het Nieuwe Steen´ and a few walls survived. Several architects provided designs for a new town hall. The choice fell on Hendrick de Keyser´s plans. The well-known architect succeeded in creating a new town hall, using the old tower and remaining parts of the walls. The new building had a very delicately balanced, almost symmetric set-up, and raised in the years 1618 - 1620. After this the building hardly changed, till in the 19th century it was drastically converted, due to administrative reorganizations which started off during the French Period (appointment of aldermen, a council and registry offices). The changes caused modernization of the larger part of the interior and also the windows and entrance. In the years between 1934 and 1939, most of the 19th century modernizations were reversed. The structure of the building was strengthened and almost all the wooden constructions in the tower were replaced by reinforced concrete. After the Second World War the town hall was more and more used for representative functions and therefore it was decided that the building would be restored into its 17th century splendour. The exterior walls were restored in 1962 - 1966, followed by the restoration of the interior in 1980 - 1981. It was not the intention to bring back the 17th century situation in detail; on the one side for pratical reasons, on the other side because many 17th century details could not be traced back. Inside the present town hall reins a 17th century atmosphere indeed, but except for the main reception room with its judgement seat and its adjoining rooms, this atmosphere is partly due to elements such as doors and doorposts that are not in accordance with the historical reality. The exterior was carefully reconstructed in a reliable way, and is now an outstanding example of 17th century architecture."