Budapest, Hungary.
No one seems to know why this is so named - it has certainly never been called on to defend anything. The stories say that in the old days this was where the fishermen defended Castle Hill from. It stands behind Matyas Church, overlooking the river and was built around 1900 by the same person who was responsible for the reconstruction of the church. There is a small fee to pay to climb up it, but it is worth it for the views. It makes for some of the finest photo opportunities in all of Budapest.