St Petersburg's two most photographed churches stand fifteen minutes apart, both operate as museums and both sell tickets. On a short trip you have to pick one — and the choice is easier than it looks, because they deliver completely different experiences.

St Isaac's Cathedral is about scale and the view from above. The Church of the Savior on Spilled Blood is about mosaics and its silhouette.

How they differ

St Isaac's is a giant. It took forty years to build and was consecrated in 1858; its dome is visible from most open ground in the city. Inside it is dark, heavy and solemn: granite, malachite and lapis lazuli, vast paintings and mosaics. The feeling is imperial grandeur rather than warmth.

The real draw, though, is the colonnade — a walkway around the base of the dome with the whole centre laid out below you: the Neva, the Admiralty, the rooftops. It is the best viewpoint in historic St Petersburg, and the ticket for it is sold separately from the cathedral itself.

The Savior on Spilled Blood is the exact opposite. Built on the spot where Alexander II was fatally wounded, it is deliberately Russian — pointedly Moscow-like and un-Petersburgian: patterned domes, tiles, ornament. Inside there are more than 7,000 square metres of mosaic, covering walls and vaults completely. It is effectively a mosaic museum: there is almost no painting, everything is laid in smalt.

The church is small and quick to see, but it leaves a strong impression — especially on a sunny day, when the mosaic starts to glow.

Which one suits you

One church for the whole trip, first time here. St Isaac's, for the colonnade. You get the cathedral and the panorama in one go, instead of hunting for a viewpoint separately.

You love detail and decoration. The Savior on Spilled Blood. Those mosaics reward long looking, and on a world scale they are a rarity.

You are afraid of heights or find stairs hard. The Savior on Spilled Blood: the colonnade means more than two hundred steps of spiral staircase, and there is no lift.

You have an hour, maybe ninety minutes. The Savior on Spilled Blood — compact, and an hour is genuinely enough. St Isaac's with the colonnade is a two-to-three-hour affair once you count the queues.

It is overcast. Then skip the colonnade: on a grey day you see little from up there, and the ticket is not worth it.

Travelling with children. The Savior on Spilled Blood: bright, colourful, quick. St Isaac's usually bores children — except for the climb, which they tend to love.

Time and tickets

Both belong to the same museum complex, but tickets are sold separately, and a combined cathedral-plus-colonnade ticket is not the same thing as a cathedral-only one. This is the single most common confusion at the entrance.

Seeing both in one day is entirely realistic: fifteen minutes on foot across Nevsky and along the Griboyedov Canal, and the walk itself is a pleasure.

What is nearby

St Isaac's sits on its own square, with the Mariinsky Palace, the Bronze Horseman and the Admiralty close by, and Palace Square and the Hermitage beyond. This is the formal, official face of the city.

The Savior on Spilled Blood stands on the Griboyedov Canal, next to the Mikhailovsky Garden, with the Russian Museum on Arts Square and the Summer Garden ten minutes away. Here St Petersburg looks cosier and more picturesque.

Opening hours, prices and evening programmes change with the season, the colonnade often keeps its own schedule, and parts of the route close in winter. Check the museum complex's official site at cathedral.ru before your visit.

The short answer

Choosing one, in clear weather: St Isaac's, and go up the colonnade. Overcast, short on time, or wary of stairs: the Savior on Spilled Blood. With half a day, see both — they are different enough that neither dulls the other.