You might want to spend some time browsing the exhibits at Bunker Museum, Museum of the World Ocean, or Amber Museum. Ruins of Koenigsberg castle, King's Gate, and Wrangel Tower are well-known local landmarks worth a visit. You can watch performances at Kaliningrad Regional Drama Theatre, Kaliningrad Regional Youth Theater for Young Spectators, and Queen Louise Kirsch Puppet Theater if you're interested in local theater.