In The Netherlands, every year on a Saturday in September it's Open Monuments Day. In 2015 it took place on September 12th. On Open Monuments Day a number of monuments in Maassluis also, one of which is the building of the National Dutch Towage Museum, open to the public. This small but very beautiful former old town hall of Maassluis built in 1676, pittoresque situated in the corner of the basin of the inner harbour, deserves without doubt the title "paramount town determining monument". Unfortunately, the designer is unknown. The building bears the characteristics of the classicism historic period and has been equipped with a hipped roof with brick-layed corner chimneys and a wooden ridge-turret. A herring-buss serves as a weather vane. The dormer-windows have been decorated with herrings, to keep the memory alive, that the wealth of the town was a result of the profitable fishery activities in those years.
During the years 1971-1973 the building was thoroughly renovated. The opening hours on Open Monuments Day of the National Dutch Towage Museum are between 11.00 and 17.00 o'clock. On this day visitors have free admittance.
Buildings that are open to the public are marked with an "Open Monumentsday" flag and a yellow poster. On the Bloemhof square is an exposition of old skills arts.
On the Market Place guided tours by guides of the Historic Association Maassluis start at 11.30 and 13.30 h. at the location of Grand cafe De Waker.