Tallinn
Designated a UNESCO World Heritage site, the Old Town of Tallinn is one of the best-preserved medieval cities in Europe. An entire day can easily be spent exploring the churches, homes and public buildings constructed from the 13th to 16th centuries by wealthy German merchants of the Hanseatic League. Other periods of history are represented by the soaring spire of St. Olaf’s Church, dating to the 12th century and dedicated to the King of Norway, and the distinctive onion domes of Alexander Nevsky Cathedral, built in the late 19th century under the reign of the Russian Empire.