Peter and Paul fortress was founded in 1703. It is the oldest
architectural set of St. Petersburg. It lost its significance as a fortress and
was a dungeon for those who were considered to be a threat to be state up untill
1917. Peter I kept his son Alexey there. Many writers and revolutionaries were
kept prisoners there: Dostoevsky, Gorky, Trotsky, the Lenin's elder brother -
Alexander. After the revolution the fortress became a museum (1924). The public
is admitted into Troitsky bastion.
St. Peter's and Paul's church was built by the architect Trezini between 1722 and 1732 it was unknown in those days for a western style to be prominent in the form of long rectangle, with a high spire (122 meters high). The baroque interior of the church differs greatly from traditional Orthodox Church of Russia. It is light and full of air with a gilded queer place for icons, which were constructed between 1722-1726.
Beside the cathedral there is a small building where the small boat of Peter the Great is kept. He sailed it in his childhood and it was this small boat which gave the start to the history of Russian Navy.
The tourists usually get into the fortress by passing St. Ioan's Gates and entering it through St. Peter's Gates, constructed in 1717-1718 by the architect Tresini as a triumphal arch with the statues of ancient Gods and later crowned with the two-headed eagle, added in 1722.
Every day at 12 o'clock the gun on the Navarsky bastion marks the Admiral hour.
Some interesting links: