The Ruïne van Brederode (Brederode Castle) are the remnants of the oldest castle (and building) in the province of Noordholland. It is located near Santpoort-Zuid, and can be visited outside the winter season.
The castle highlights a very interesting period in the history of Holland, from before the time that Amsterdam was just a small, unimportant settlement. This castle is practically the only remnant from this medieval period.
The castle was built in the 13th century (see Wikipedia).
It is the first building that became an officially listed historic state monument in the Netherlands, in the 19th century.
Ruïne van Brederode (Brederode Castle ruins)