Catacombs
From MHWiki
A potential new area of the game. As of January 29, 2009 there has been no official announcement of the area. However, if one reads the description of the Arcane trap on the Trapsmith page, it makes reference to an area called the Catacombs.
It is believed that the area that will be opened through the repair of the Tattered Mousoleum Map will be the Catacombs.
Description and Requirements
If this is indeed the next area, the description of the map repair from the Cartographer in the Bazaar indicates that the hunter will need to be the level of Legendary to enter.