This magnificent four-arched gatehouse on the waterfront was built as a palace for Polish monarchs. No Polish king ever stayed in the building, but Lech Wałęsa has his office here: you'll see his nameplates on the walls of the gate. The gate leads to the Green Bridge, which spans the Motława River and which used to be raised to stop the riff-raff from getting into the Old Town. Following a good scrub and a careful renovation the gate now bears an uncanny resemblance to Amsterdam's central train station, and is frequently home to passing exhibitions.