What is the longest place name in Wales and where is this village?

llanfairpwllgwyngyllgogerychwyrndrob wllllantysiliogogogoch (withour the space); which translates as :

"The church of St. Mary in the hollow of white hazel trees near the rapid whirlpool by St. Tysilio's of the red cave"

It's on the North Wales island of Anglesey