Berlin is Germany's capital, a cross-border run from western Poland. Brandenburg Gate, the Reichstag, and Museum Island are the first-timer circuit; Wall traces and neighbourhoods like Kreuzberg show the rest.
It is huge compared with Pomeranian towns: several days if you want more than a photo at the Gate. From Gdańsk the drive is a long European route via western Poland. Private transfer skips station changes with luggage.