Holstentor
If Holstentor seems familiar, it's possible you've seen it on a German two-euro coin. Holstentor (also known as Holsten Tor or Holsten Gate) was built in the 15th century as part of the Hanseatic city of Lübeck's medieval defenses. It is one of only two of the city's original four gates, the other being Burgtor.
These city gates started out as modest gates that were gradually strengthened through time to include an outside, middle, and inner gate. Only parts of these historic city gates survive today. The previous Interior Citadel Gate is now known as the Citadel Gate; the Middle and Outer Citadel Gates are no longer in use. All three Mill Gates have vanished totally. The current Holsten Gate was formerly known as the Middle Holsten Gate; there was also an (earlier) Inner Holsten Gate, an Outer Holsten Gate, and a fourth gate, known as the Second Outer Holsten Gate. As a result, the Holsten Gate's history is really the history of four gates in succession, but only one of them is still standing.
Holstentor is now one of the many structures that make up the UNESCO Hanseatic City of Lubeck complex. The city museum of Lübeck is housed in a medieval treasure that seems like it came right out of a storybook.
Location: Holstentorplatz, 23552 Lübeck