The St. Isaac's Cathedral is the largest Orthodox Church in St. Petersburg and one of the highest domed structures in the world.
43 rocks of minerals were used during the construction. The dome itself is made of metal, and for its gilding was taken about 100 kg of red gold. The St. Isaac's Cathedral is sometimes called a museum of colored stones: the interior walls are faced with white marble with a decorative panel of green and yellow marble, jasper and porphyry.
Karl Bryullov, painted the main dome from the inside and Vasily Shebuyev, Fedor Bruni, Ivan Vitali and many famous artists and sculptors worked on the other interior of the temple.
The height of the cathedral is 101.5 m, about 12,000 people can be in the temple at the same time.
The Colonnade of St. Isaac's Cathedral is worth a special attention. It is an overview of the historical center of St. Petersburg from a height of 43 meters. You need to get to the observation deck through 562 steps, but it is worth it: you will have a 360-degree view of St. Petersburg. From the colonnade you can see all the major sights: the Neva River, St. Isaac’s Palace Square, the Peter and Paul Fortress and many others.
The Colonnade is the least loaded in the mornings on weekdays, and rather crowdy - at lunch and in the evening on holidays. There is also such factor as sunny / overcast weather - when the sun is shining, there are slightly more people.
Above all, do not forget the camera, warm clothes and comfortable shoes.