You'll want to browse the collections at B-413 Submarine Museum, Museum of the World Ocean, and Bunker Museum. Honey Bridge, Brandenburg Gate, and Ruins of Koenigsberg castle are monuments to see when you're exploring the area around Friedrichsburg Gate. You can watch performances at Kaliningrad Regional Drama Theatre, Kaliningrad Regional Philharmonic Hall, and Art House Concert and Theater Complex if you're interested in local theater.