Malian Temple

Malian Temple was a major Temple located on the Ice Kingdom and Candy Kingdom border, that was once the main capital for the Irocadians, who were around hundreds of years before the founding of the Candy Kingdom, and Princess Bubblegum's birth, The Irocadians were the final remnants of Humans, following the Mushroom War, but a giant Earthquake, wiped most of them out, leaving its cities including Malian Temple abandoned and empty, for the years to come.

Trivia

 * According to Adventure Time Insurrection, the Malian Temple was known to have been around hundreds of years before the founding of the Candy Kingdom, and how it was once a city hall or governmental structure for the remaining Humans that plagued the Continent before Ooo was formed, hinting that Malian Temple is far older than any of the Adventure time Cast members including Bonnibel Bubblegum or her mother...