Three historic cathedrals, crowned by pristine white towers with golden domes, surround an open square. Hushed crowds of tourists edge their way past the tombs of royal dynasties, craning their necks to see the centuries-old religious art that covers the soaring interiors.

All this in the middle of the Kremlin.

For an American who grew up in the Cold War era, it’s a slap-your-head surprise. Come to Moscow expecting the grim, gray capital of a police state, and find a throbbing metropolis.

Moscow was the first stop on a 13-day cruise that took us 1,123 miles northwest to St. Petersburg.

On a sunny June day, Moscow was positively electric, flirtatious even. Flowers arranged on arched metal sculptures covered pedestrian walkways. Tourist boats plied the Moscow River. Down another street, adults cavorted on swings outside a concert hall.

It was all positively whimsical. And that’s before you see the one Moscow landmark known the world over for its candy-colored onion domes, St. Basil’s Cathedral on Red Square.

This is when you realize that the Kremlin isn’t just a building. It’s a 60-plus-acre stone-walled fortress containing an armory, several palaces and the neoclassical Senate building.

A river cruise is an ideal way for first-time visitors to get a sense of this vast nation. Even with our 13-day cruise, we only got an up-close look at a small part of it, what is usually known as European Russia.

Aboard Viking River Cruises’ 95-stateroom Ingvar, we spent four days in Moscow and four days in St. Petersburg, and had some of the most compelling experiences in between.

Visiting the small Volga River town of Uglich, we shopped for souvenirs at an outdoor market and met a local woman who hosts small groups of tourists for brief home visits. She served us cheese, bread, cucumbers and cakes, along with tea and a bit of her family’s searing moonshine.

I signed up for a typical Russian bathhouse experience in the town of Mandrogy. Inside the wooden banya, our group of five women perched on a raised wooden bench while a Russian man tossed water on heated stones to send the steam and temperature rising. He gently patted our limbs and backs with birch branches before telling us to go outside to the pier and jump into the icy cold Svir River. We did, some naked underneath the towels we shed at the pier, others in panties or bathing suits. Two sessions of steam, birch branches and river plunge, and it was time to sip some hot tea. It was simultaneously invigorating and relaxing.

The last stop on the cruise was St. Petersburg, Russia’s cultural heart. It’s worth a journey if only to see the Hermitage Museum, which rivals the Louvre. Many of the Hermitage galleries are in the Winter Palace, the main residence of Russia’s rulers in the 18th and 19th centuries. The storming of the palace in 1917 marked the beginning of the Russian Revolution.

The city center is laced by canals and straddles the River Neva. Peter and his successors brought in architects from Italy and France who put their stamp on the city center; many of the parks and historic buildings wouldn’t be out of place in London or Paris.

It’s the city’s Western European feel that makes its most striking building such an interesting contrast. The Church of Our Savior on Spilled Blood, finished in 1907, looks straight out of medieval Russia, encrusted with intricate mosaics and icons and topped by a breathtaking cluster of colorful onion domes.

The church derives its gory name from its reason for being. It marks the spot where Czar Alexander II was blown up by revolutionaries in 1881. Alexander’s son decided that a great church must shelter the spot where his father’s blood was spilled. Josef Stalin later used the building to store potatoes.

If you go

Viking River Cruises operates its Waterways of the Tsars 13-day cruises between May and October, with prices starting at $5,099 a person; vikingrivercruises.com.