Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch
Yes, that is indeed the longest place name that the world has to offer and we were there. The city itself is relatively unspectacular, but the whole world knows the train station and the sign. Translated, it means:
St. Mary's Church
(Llanfair) in a hollow
(pwll) of white hazels
(gwyn gyll) near the swift whirlpool
(y chwyrn drobwll) and the
Tysilio Church (llantysilio) with the red cave
(gogo goch).
Sister cities are the town "Y" in
France and "Ee" in the Netherlands 😂
By the way, the place did not always have this name, at the end of the 19th century someone came up with the idea of adding a description to the actual place name and creating a new place name from it. The reason was simple, they wanted to become better known for trade and to persuade the railway to build a station there through fame. It worked, as you can see from the beautiful Victorian train station building.