Ruine Oude Matthiaskerk in Teylingen

You're standing at the Old Tower in Warmond, a ruined church in the middle of an old churchyard. Start by looking at the foot of the tower. You'll see huge medieval bricks and chunks of pale tufa stone. That gives away its age. In its current form the tower probably dates from the fifteenth century. But notice how the church was built around the tower, which means the tower is older than the walls beside it.