The Church of the Annunciation, a genuine necropolis, contains the tombs of members of the imperial family, including the son and sister of Peter the Great, and those of the Empire's major figures. Designed in the early 18C by Domenico Trezzini, the first architect and urban planner of St Petersburg, it features a high church, devoted to Saint Alexander Nevsky that houses a museum of urban sculpture and a lower church dedicated to the Annunciation.