St. Isaac Cathedral is an outstanding church, unique architectural and engineering masterpiece, world’s biggest domed cathedral. The diameter of the cathedral dome is 21.8 meters, the height of the building is 101.5 meters, 72 columns were mounted inside it and the weight of each column is more than 100 tons. The construction of the cathedral lasted for exactly 40 years. 20 kinds of decorative stones were used for the decoration of the St. Isaac Cathedral interior, such as marble of various kinds, malachite and lapis lazuli. The unique mosaic survived up to the present day. This outstanding architectural masterpiece occupies the area of 600 square meters. The great world sculptors created the frescos and sculptures of the cathedral. Now the divine service is ministered in the cathedral, and it is also functioning as a museum. One of the tourist attractions of St. Isaac cathedral is climbing the colonnade and viewing Saint Petersburg panorama from the height of 43 meters.