Riga was the last of 3 Baltic capitals that I visited, and I have a hard time making up my mind on which is the nicest. Vilnius is a Central European, Catholic city with Baroque architecture, similar to Krakow, while Tallinn is a Northern European, Protestant city with brick buildings. Riga is somewhere in between, reflecting its geographic position, but a bit closer in most aspects to Tallinn than to Vilnius. Like the others, it is an immaculately clean city with a fine historic centre full of interesting buildings, most of which are clustered in the medieval core (particularly the Dome Cathedral and St. Peter's Church with its lookout tower). The cherry on Riga's cake is the large Art Nouveau/Jugendstil district to the north of the centre, where you can walk around for a long time admiring the stunning facades. A good place to start is the Art Nouveau Museum, which is housed in an original buiilding and features a unique staircase. I only had a weekend in Riga, but I'm sure that you can easily fill several days exploring this interesting city,.