This is the Alexander Nevski Cathedral, the main center for Russian Orthodoxy in Estonia. Built in 1900 and designed by a St. Petersburg architect. Nevsky was a Russian hero who defeated the Knights of Tuetonic Order in the 13th century. Legend has it the structural damage the church has suffered over the years is because it was built on the grave of a local hero, Kalevipoeg. The inside was just a beautiful, but camera's weren't allowed. It was busy with almost as many worshipers as tourists.