Traveling Eastern Europe, any recommendations?

In Riga, you should visit the old town and the zoo(one of the biggest in Europe), but you should be good at speaking Russian, because there are a lot of people, who don't understand Russian. In Lithuania you should visit the cathedral of Vilnius and it's catacombs. You should also visit Gediminas' castle. If you want to go shoping, you should visit Akropolis and Europa