28 Peter and Paul Cathedral - Saint Petersburg, Russia
Commissioned by Peter the Great, the Cathedral of Saints Peter and Paul is located inside the Peter and Paul Fortress in Saint Petersburg, Russia.
Built on Zayachy Island, between 1712 and 1733, the cathedral's bell tower is the world's tallest Orthodox bell tower. It also acts as a lightning rod protecting the cathedral.
The cathedral houses the remains of most of the Russian emperors and empresses from Peter the Great to Nicholas II; including Catherine the Great, Empress of Russia for 34 years.
The Historic Centre of Saint Petersburg and Related Groups of Monuments was declared a World Heritage Site by UNESCO in 1991.