Saint Isaac's Cathedral

Auguste de Montferrand built St Isaac's between 1818 and 1858 - forty years, on ground that is marsh, requiring tens of thousands of timber piles driven into it before anything could rise. The forty-eight granite columns of the porticoes, each about seventeen metres and over a hundred tonnes, were cut in Finland, shipped in and raised by winch in under an hour each, before the walls were built around them. The dome is gilded with about a hundred kilograms of gold, applied by a mercury process that killed a substantial number of the workers, and it reaches 101 metres. Inside are malachite and lapis columns, mosaic altarpieces and painting; a Foucault pendulum hung from the dome in the Soviet period when it was a museum of atheism, and has since been removed. The colonnade at the base of the dome is walkable on 262 steps, and gives the best rooftop view of the city.

What you actually see

• The granite columns - forty-eight monoliths of over a hundred tonnes each, raised before the walls.
• The dome - 101 metres, gilded by a mercury process that killed workers.
• The colonnade walk - 262 steps to a walkway with the best view of the city.
• The interior stone - malachite and lapis columns with mosaic altarpieces.

When to go

Year-round. One to two hours including the colonnade. Summer evening colonnade sessions run late and are the best time for the view.

Honest expectations

The colonnade is a separate ticket and 262 steps with no lift. Queues in season. The gilding's human cost is real and not much discussed on site. It functions mainly as a museum, with limited services.

Nearby

The Bronze Horseman and the Admiralty are a short walk; the Hermitage is north.