Visit St.Isaac's - the main and the largest Russian Orthodox Cathedral. Now it is a Museum. During this Tour of St. Petersburg we show you the most significant sights in the city center close up, giving you some of the historical background and the stories that lie behind the facades of this most fascinating city with a knowledgeable guide. St. Isaac's Cathedral built in St. Petersburg in 1858 by the architect Montferrand, the fourth highest among the world's cathedrals under the single cupolas. It follows St Peter's in Rome, St. Paul's in London and Santa Maria del Fiorre in Florence. A wonderful guided walk excursion! The observation platform at the foot of the dome commands a fine view over St. Petersburg and its surroundings!