Welcome to Shureimon, written 守礼門 in Japanese, the vermilion gate that greets visitors at the edge of Shuri Castle in Naha, on the island of Okinawa. You are standing in the old royal town of Shuri, on a hilltop that once looked down over the harbor that made the Ryukyu Kingdom wealthy. This gate stands just outside Kankaimon, the castle's welcome gate, at the eastern end of a great avenue that runs east to west through Shuri. In Japanese castle terms, it plays the role of the main front gate. It is also the second of the castle's ceremonial gates, which is why older names call it the upper torii or the upper Ayajo gate. Over the next few minutes we will look at who built it, what its name and its famous sign really mean, how its design borrows from China, and how it came back after the war to become one of the best-known images of Okinawa.