Dragonspiral Tower

Dragonspiral Tower is an old tower where Zekrom / Reshiram was sealed in the Dark Stone / Light Stone after the war thousands of years ago, until it was awoken by N. It is located in the western part of Unova, just above Icirrus City. Though it is not known who built it or when it was built, it is the oldest structure in Unova. It is said this is where Legendary Pokémon are created and slumber. In Pokémon Black and White, the first accessible portion of Dragonspiral Tower is the entrance north of Icirrus City, due to the tower itself being surrounded by a moat that cannot be traversed using Surf.