St. Isaac's Cathedral is an outstanding example of late classicism, which is already evident new directions (the neo-Byzantine style, eclecticism), and a unique architectural structure and high-rise dominant of the city.
His appearance to St. Isaac's Cathedral is obliged to Peter I. Peter was born on may 30, the day of Saint Isaac of Dalmatia, a Byzantine monk, once canonized. The temple dedicated to this Saint was built at the Admiralty. For the new Church it was decided to convert the former Admiralty drawing. In the summer of 1707 South of the yard there was a small wooden building roofed with boards with ten mica Windows. It is here February 19, 1712 Peter I was married to his wife Catherine.
The height of the Cathedral 101.5 m, the length and width — about 100 meters. The outer diameter of the dome — 25,8 m. the Building is decorated with 112 monolithic granite columns of different sizes. The walls are faced with light-grey Ruskeala marble. When installing the columns were wooden construction engineer A. Betancourt. On the frieze of one of the porches you can see a sculpture of the architect Montferrand.
The phrase placed in the frieze of the North portico, — "o Lord, in thy strength the king will rejoice"— can be considered the expression of the idea of the entire structure.
The statue, located on the corners and tops of pediments represent the 12 apostles (sculptor Vitali), the closest disciples of Jesus Christ, and peaks crowned with statues of the evangelists, that is, the authors of the Gospels — the first 4 books of the New Testament, which tells about the teachings and life of Jesus.