St. Isaac’s Cathedral is an outstanding monument of Russian architecture of the 19th century and one of the greatest dome constructions in the world, smaller in size only in comparison with the Cathedral of St. Peter in Rome, St. Paul’s Cathedral in London and Santa Maria del Fiore Cathedral in Florence
Grandness of this temple is shown by its size: the height of the building is 101.5 m; the length is 111.2 m; and the width is 97.6 m.
The cathedral is one of the dominant buildings of St. Petersburg and the second in height after the Sts. Peter and Paul Cathedral. Its monumental and majestic image creates a unique accent in the city’s skyline and serves as much a landmark of the northern capital, as the spire of the Cathedral in the Peter and Paul Fortress and a gold ship atop of the Admiralty.