The original Admiralty was one of the first structures to be built in St Petersburg. It was designed to be a dockyard, where some of the first ships of Russia's Baltic fleet were built (some with the participation of Tsar Peter himself who, was an expert in shipbuilding). The Admiralty was also fortified to be an extra defense for the newly acquired territory of the Neva delta.
The Admiralty building we see today was built between 1806 and 1823 by the architect Adrian Zakharov. He maintained the original plan of the building, but turned it into a marvelous example of the Russian Empire style, with rows of white columns, wonderful relief detail and numerous statues. The gilded spire of the Admiralty (and particularly its weather-vane korablik - "the little ship") is another of St. Petersburg's famous landmarks. The Admiralty tower, topped with its golden spire, is the focal point of three of the city's main streets; Nevsky Propect, Gorokhovaia Street and Voznesensky Prospekt, and can be seen along the entire length of each one.
The Admiralty was Russia's Naval Headquarters until 1917, and now serves as a naval college. The gardens in front of the Admiralty are particularly beautiful in summer, and you might choose to walk through them on your way from the Hermitage to the "Bronze Horseman" and St Isaac's.