We have learned quite a lot about the history of Eastern Europe as well - most of which was not covered in high school history class... We visited the Warsaw Uprising museum, which described an unsuccessful rebellion against the Germans in 1944. The Poles hoped for support from the Allies, but had to surrender after two months of fighting and hundreds of thousands of deaths. A few months later, the Soviets showed up, and the Poles again helped fight against the Germans. However, Stalin was keen on keeping Poland under his rule, so he arrested and deported the Polish war heroes, to keep them from leading a movement for independence.
In Vilnius (Lithuania), we visited the KGB museum, which mostly covered Lithuania's fight for independence from the USSR after WWII. They fought for nearly ten years, always hoping for support from the West, but never receiving it. The museum was housed in the old KGB prison, and the basement was unchanged, complete with water torture and execution chambers. We also visited a Holocaust exhibit and Jewish cemetery (there were large Jewish groups in Poland and Lithuania pre-WWII).
To avoid focusing only on the depressing side of Eastern Europe, yesterday we went to Trakai Castle - on an island in a lake near Vilnius. Today, we continue on to Riga, to meet up with our Latvian friend Ieva.