Tubbo's secret bunker

Tubbo's secret bunker is a location beneath Manberg and L'Manberg created and used by Tubbo as his home.

Pre-election
Just before the election results were announced, Tubbo revealed the bunker beneath what was then L'Manberg to Wilbur and Tommy. He'd built it in case anything went wrong during the election, and Tommy and Wilbur used it to escape when they were exiled from Manberg.

Post election
The bunker was used to store Tubbo's items along with his secret archives of the history of L'Manberg and the greater server. He had several important relics stored within the archives including several books from the War for L'Manbergian Independence to the marriage license of George and Ninja.

The bunker was eventually discovered by Schlatt along with the Underground Prime Path. Tubbo was able to play this off, telling Schlatt that the bunker and path had been built for him to farm Totems of Undying from a nearby watchtower.

Post Manberg vs Pogtopia War
Part of the bunker was damaged during the explosion and the withers, but none of the prized contents such as the book collection were damaged. The books were eventually moved to Ghostbur's library.