Montferrand's design was criticised by some members of the commission for the dry and allegedly boring rhythm of its four identical pedimented octastyle porticos.

With the fall of communism, the museum was removed and regular worship activity has resumed in the cathedral, but only in the left-hand side chapel.

The key protocols of the transfer were defined by the order issued by St. Petersburg's Committee on Property Relations on 30 December 2016.

The transfer of Saint Isaac's Cathedral in use the ROC agreed in January 2017, but the decision has caused discontent of the townspeople, who defended the status of the museum.

The columns were made in Pyterlahti quarry in Virolahti, Finland The cathedral's main dome rises 101.5 metres (333 ft); its exterior is gilded.

Internal features such as columns, pilasters, floor, and statue of Montferrand are composed of multicolored granites and marbles gathered from all parts of Russia.

When these paintings began to deteriorate due to the cold, damp conditions inside the cathedral, Montferrand ordered them to be painstakingly reproduced as mosaics, a technique introduced in Russia by Mikhail Lomonosov.

The building rests on 10,000 tree trunks[8] that were sunk by a large number of workers into the marshy banks upon which the cathedral is situated.

The dome was gilded by a technique similar to spraypainting; the solution used included toxic mercury, the vapors of which caused the deaths of sixty workers.

[23][24] The dozen gilded statues of angels, each six metres tall, facing each other across the interior of the rotunda, were constructed using galvanoplastic technology,[8] making them only millimeters thick and very lightweight.

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.