Look closely at the facade of this sober residence known locally as the 'House with the Blood Stains'. After losing his fortune, six-time mayor and diplomat Coenraad van Beuningen lost his mind and scribbled graffiti here, allegedly in his own blood, and his unfathomable message – including Hebrew letters and obscure Kabbalah symbols – from the 17th century is still faintly visible.

Well-to-do businessman Gijsbert Dommer commissioned this house from 1671, but it's the mad mayor who is better known today.