The Schreierstoren (in English also known as 'Weepers' Tower' - but this is an incorrect translation) is a remnant of Amsterdam's medieval city wall.
It was built as a defense tower in 1481, and is thus one of the oldest buildings in Amsterdam.
The tower has some fame as the location from which Henry Hudson left for Northern America - an expedition which would lead to the discovery of what is now called Manhattan.
Inside the building is a cafe.
Schreierstoren