The Russian name for the church is Isaakievskiy Sobor (Исаа́киевский Собо́р).
For historians and architecture buffs:
Saint Isaac’s was originally built as a place of worship, designed to accommodate 14,000 standing worshipers. The Soviet government closed the church in the early 1930’s and reopened it as a museum. It has remained a museum ever since, with church services only on major ecclesiastical occasions.
Scottish engineers used technological innovations in the construction of the building. The portico columns were raised with the use of large wooden frameworks before the walls were erected. The building rests on 10,000 tree trunks that were sunk into the marshy banks.
The dome was gilded by a technique similar to spray painting. Unfortunately the solution used included toxic mercury. The vapors caused the deaths of sixty workers.
There are a dozen gilded statues of angels, each 20 feet tall, facing each other across the interior of the rotunda. The angels were constructed using galvanoplastic technology, making them only millimeters thick and very lightweight. St. Isaac’s Cathedral represents the first use of this technique in architecture.
The massive granite columns are made of single pieces of red granite. More than 331 pounds of gold leaf were used to cover the dome. The dome has never had to be regilded. It continues to gleam after all these years.
St. Isaac’s Cathedral once housed one of the few working Foucault’s Pendulums in the world . It clearly demonstrated the rotation of the Earth, but the Pendulum was later dismantled.
During the construction, the architect fell from the scaffolds when the workers were lifting 64-ton columns to their full height. He survived because nearby workers managed to catch him.
The meticulous and painstakingly detailed work constructing the St. Isaac’s Cathedral took 40 years to complete. This extended construction left an expression in the Finnish language, rakentaa kuin Iisakin kirkkoa (“to build like St. Isaac’s Church”), for lengthy and never-ending megaprojects.