Quote: St. Isaac's is also the third largest church in the world, after St. Peter's in Rome and St. Paul's in London. The gilded dome is a landmark that can be seen all over the city. The outside is quite sober looking, with dark columns on each side. The bronze doors reminded me of the doors at the Duomo in Florence. Inside there are paintings and mosaics everywhere.
From journals Cruise to the Baltic States and St. Petersburg

Quote: We took a walk through the very neat Admiralty Gardens. At lunchtime, the park was exceptionally quiet although there was proof that someone had been hard at work as numerous, small leaf piles had been arranged along the walkways as flowerbeds were readied for spring. We lamented the fact that we’d arrived too early to see the gardens at their best. In April the grass was grayish brown and the parks looked dusty and lifeless.

We watched a group of navy cadets jog by, passing in front of The Admiralty. The building was constructed in 1823 as the administrative headquarters of the Russian Navy and has served as a naval college since 1923.

A short walk from the gardens led us to St. Isaac’s Cathedral, one of Russia’s largest Orthodox cathedrals. It’s a bronze dome and red granite columns tower over Isaakievskaia Square, dwarfing the Monument to Tsar Nikolai I, which stands in its centre. Both cathedral and monument were designed by Auguste de Montferrand, a French architect who was refused burial rights in the cathedral because of his Roman Catholic birth. Considering the forty years it took to construct, and the magnificence of the finished structure, you can understand why he felt so strongly about spending his afterlife there too.

We bought a ticket to ascend to the colonnade, which costs around $4 for the colonnade only (the interior museum is additional). It’s not a particularly long climb, about 300 steps if you want to count, and you can peak through windows and see a part of the striking interior. Walking around the colonnade you get 360-degree views over St. Petersburg, including the Hermitage, the Admiralty and Gardens, and the Peter and Paul fortress across the Neva. At the time of our visit, photography was permitted on the colonnade but not inside the cathedral.

This immense cathedral, which can accommodate 14,000 worshipers, has served as a museum since the 1930s and services are held only on significant ecclesiastical holidays. It’s open from 11am to 6pm daily, except for Wednesday.

Regrettably we were pushed for time and didn’t venture inside but from the small peeks we did get, the famed mosaic work and paintings looked breathtaking and well worth spending the additional time and money.

I’d actually recommend dedicating an entire day to this area and taking in the Yusupov Palace in the afternoon, which is a fairly short walk south and then west along the Moyka Canal.
From journals St. Petersburg in all its Faded Glory

Quote: Its immaculate view is absolutely gorgeous. It separates two emperors of the Russian Empire, Peter the Great and Nicolai I. There are two statues. Both men are sitting on horses. One pursues another.
From journals St Petersburg

Quote: This is really a must. The cathedral has this appearance of greatness about it that is just remarkable. The construction of the cathedral took 20 years and its architect Montferrand died right after it was built as if just hanging on to see his child in all its glory. There is a small exhibit inside the cathedral about the history of its construction. As all the orthodox churches it has the golden cupola. During the World War II it was covered with fabric to prevent the Nazi planes from bombing the cathedral. Yet if you walk along the columns you can see bullets stuck in the red granite. This is just a small reminder of the war that was now over 50 years ago.

The inside of the cathdral is really grandious. The ceiling was painted by a very famous Russian painter Karl Bryullov. The ceiling is incredible, it contains all the main themes from the Bible, the most recognizable of which are Adam and Eve, and the 4 prophets. The walls are covered with the mosaics which were created by slave painters. Each square in the mosaic is about 1/2 inch by 1/2 inch and every mosaic took about 3-4 years to make. Also if you stay inside long enough and listen to different tours you might be able to hear the story of at least 2 of the 4 gates in the cathedral.

If it's not windy which is quite rare, you might be able to climb to the collonade and get a panoramic view of the city.

From journals Travels to Russia - St Petersburg