There is the Soviet War Memorial in Treptower Park commemorating Soviet soldiers who fell in the Battle of Berlin. Its granite flags feature the text in both Russian and German reading, “Eternal glory to the Soviet soldiers who laid down their lives in the struggle for the liberation of Humanity”. The sarcophagi are empty, while the soldiers are buried in the earth along the Memory Alley. As I'm a Russian, It is my human duty to regularly lay flowers there.
Today Treptower Park is a great place for picnics, jogging, bike riding and strolls. It’s a great idea to rent a boat and make a short journey along the Spree, e.g. to reach the Isle of Youth to enjoy the time in a café. On weekends a flea market is open in the park. You're very welcome to bargain.