The Memorial to the Murdered Jews of Europe or Holocaust Memorial is opposite the Tiergarten and between Potzdamer Platz and Brandenberg Tor.
The two hectare site is covered with 2,711 stelae, basically concrete slabs. The whole effect is quite eerie. Near the outside the slabs are short and people are sitting on them having lunch or chatting about their day. As you move into the memorial however the ground undulates and the slabs get taller so its easy to be isolated from the outside world within the massive slabs.