St. Petersburg, Russia
Peter and Paul Fortress is located on the north side of river Neva, occupying a tiny island. I went here on a rainy Sunday, and the place was full of tourist groups and other visitors.
The fortress is the original citadel of St. Petersburg, Russia and was founded by Peter the Great in 1703. The fort was built during the Northern War in order to protect the city from Sweedish attacks, but this never materialised. The fort was then used as a prison for high-profile prisoners including famous writers Dostoevsky and Gorky. After the Russian Revolution, the fortress was converted to a museum. Damage done by the Germans during WW2 was repaired and old glory of the fortress was restored.
I did not go inside the cathedral because it was getting late and by then I had seen enough of Orthodox churches. The distinguishing 122m tall golden spire of this cathedral is a landmark that can be seen from most places of the city. Most of the Tsars were buried here.
Entry to the premises is free but if you want to enter any buildings, the ticket costs RUR 60 (in 2008) for students.
I distinctly remember sitting on a bench outside the Peter and Paul Monastery and listening to the orthodox church bell music. It went on for few minutes and the tune was wonderful.