The headquarters of the Duskwardens is the Duskwarden Guildhouse: a squat building in the district of Bis marked with a placard of the Duskwardens' Twisted Door badge. Within are a few offices for ranking officials of the group, barracks for new recruits (or any member with no other place to sleep), workshops, and a modest store of equipment.1
The Map Room, while not a well-kept secret by any means, is generally not open to the public; anyone seeking access to the Duskwardens' superlative library of charts and maps of the Undercity amassed over the centuries would likely be charged a substantial fee for such access.1
In the Guildhouse's basement is a tunnel mouth the Duskwardens affectionately call the Hole, one of the few remaining entrances to the Undercity. The Hole is guarded around the clock and sealed with a large metal screw-plug when it is not in use. The Hole serves the Duskwardens both as an entry point from which to launch exploratory or other missions and an access to the Duskwardens' training chambers, where recruits are taught how to fight and survive in subterranean conditions and applicants are tested for nerve and ability.1
For additional resources, see the Meta page.