The gardens of the Winter Palace, St Petersburg, are little known, as the great imperial palace of the Romanovs was never intended to have gardens. As the Tsar's principal residence, situated in the capital, it was very much intended as a symbol of power rather than a place of relaxation and pleasure.
Bordered by the River Neva on its northern side and Palace Square on its southern, the Winter Palace was devoid of space for gardens; however, the last two empresses of Russia each created gardens from previously paved areas.
Wikipedia https://en.wikipedia.org/wiki/Gardens_of_the_Winter_Palace
Coordinates 59°56'22.686" N 30°18'41.619" E