One of the largest Eastern Orthodox cathedrals in the world, Alexander Nevsky was built between 1882 and 1912 to honor the Russian soldiers who died liberating Bulgaria from Ottoman rule. The cathedral's gold-plated dome rises 45 meters high, and its interior features stunning Italian marble, Brazilian onyx, and elaborate frescoes. The crypt houses an impressive collection of Orthodox icons spanning 800 years.
Visit early morning to avoid crowds. The crypt icon museum is worth the small entrance fee. Photography is not allowed inside the main church.