Van Bleyswijck's account makes it plain that the new Guildhouse was converted from the Old Men's House chapel "which had latterly served as a cloth-testing hall." It was a single room ("a very large and airy room"), and what is more, a room on the first floor. As Montias describes, "The burgomasters of Delft, at their session of 3 September 1661, had consented 'at the repeated demand of the St Lucas guild... to allow the guild the use of the great upstairs hall with a small room beside it... in the Old Men and Women's House on the Voldersgracht'"(10). The building was extensively altered but not completely replaced from the ground up.

This explains some otherwise strange stylistic features of the Guildhall facade as seen in Rademaker's drawing. The upper storey is all beautifully classical and symmetrical, but the lower floor has a jumble of different-sized and asymmetrically-placed windows; there is a shop or stall with a lean-to roof at the left; the main door is not central; and, oddest of all perhaps, the new pilasters supporting the pediment are not brought down to the ground, but are chopped off and held by brackets at first floor level. The upper floor has been remodelled, but the ground floor remains as it was before 1661.

Rademaker's drawing, though essentially correct as regards the general disposition of the architectural features included, is quite misleading about size and shape. This becomes clear when one compares it with a photograph of the Guildhall, taken around 1875 and reproduced by Swillens himself (Figure 9)(11). Here we see the building obliquely, looking west, from a vantage-point across the Voldersgracht. The pediment has gone, but the four windows of the hall still have their festoons beneath, and the two pilasters also remain. It is immediately obvious that the proportions of the building are quite wrong in Rademaker's version. He shows the first floor windows of the Hall much too small, and he has much wider expanses of brickwork at extreme right and left, and between upper and lower storey windows, than does the building itself(12).

It is possible to reconstruct a reasonably accurate frontal view of this facade, working from the photograph. The precise dimensions in plan are given by the 1830 taxation map. The heights can be scaled from the figure of the policeman in the photo. The stone swags now in Amsterdam provide another means for checking the scale(13). Figure 10 shows the result. (It indicates, among other things, that Lamberts's drawing of 1820 is a more reliable guide than Rademaker's.) We can recognise the off-centre arched doorway with its stone quoins, and one of the pair of triple-light windows to the right of this door. The second of these triple lights seems by the 19th century to have been made into a sash window of the same overall width but greater height. A new door and another small window, neither of which appears in Rademaker's drawing, have also been opened in the right-hand half of the facade. Much of the brickwork has been rendered.