A few days ago, I took the train to see a monument that I had heard about: St. Nikolai's Church, in Hamburg:
St. Niolai Church in Hamburg (or Nikolaikirche) was finished in 1863, and was the tallest building in the world for a few years.
It was largely destroyed in July 1943 when Allied forces heavily bombed the city. While the city did house a naval base, many parts of the city (including some predominantly civilian areas) was leveled.
Today, what's left of the main spire and the nave are open to the public, and has been turned into a memorial.
The spire is covered in soot, and still bears the scars from Allied bomb shrapnel, and stands as a testament to the horrors of war.
For a few euro, you can ride an elevator to the top of the spire, where there's a small observation deck and some information about the church's construction, and the bombing campaign that destroyed most of the city. The view really is quite impressive: