St. Isaac's Cathedral, one of the world's largest cathedrals was designed by Auguste de Montferrand in 1816 and finished in 1858.

The construction of the colossal was a major engineering feat.

24,000 wooden piles were sunk into the marshy ground to support its weight of 300,000 tonnes and 48 columns were hauled into place.

It is beautifully decorated inside.

We both thought that it had been cleaned up and seemed much lighter inside than when we visited it in 1999.

The silver dove hanging in the cupola at the very top of the dome is a symbol of the Holy Spirit.

Malachite columns frame the icons.

About 16 tonnes of malachite decorate the cathedral.

Adam and Eve.