It's a bit of a maze, unless you hadn't noticed. ~Jay Thorntree
Headquarters, or PPC HQ, is the base of operations for the Protectors of the Plot Continuum. Most of the Departments are based there, and all Agents have their Response Centres in HQ. The complex has been invaded on numerous occasions.
Navigation around HQ is tricky, even for experienced agents. Places, such as Response Centres, have no fixed location in the usual sense. A map of HQ exists; however, it is a complicated electronic device designed to work in six dimensions (in which, it is claimed, the layout of HQ is perfectly simple), and is limited to a few copies, jealously guarded by the Flowers. Most Agents do not know of its existence, and only Flowers can see in all six dimensions necessary at once.
Rooms are not numbered in a logical manner either, meaning that you can find RC#198 between RC#45b and RC#Alpha-Six-Nine-Five, for example. Adding to the confusion is the interior decoration of HQ; Generic Grey Wall with Generic Grey Floor with the occasional spatter of blood and glitter (or glittery blood) and weapons scarring from past incidents. There are few defining features to show an inexperienced Agent the way.
There is one hard and fast rule to navigating the corridors of the PPC: if you think of where you are going, then you will never arrive there. If you have to venture into the corridors, then you should always carry a distraction, be it music, a book, or another Agent. If the batteries on your music player are dead, your books are all missing, and your partner objects to being carried, then don't be afraid to hum or sing as loudly as you like. No one will think you are any more insane than the other denizens of HQ. If you are sufficiently distracted, then you will surely reach your goal, even if you don't want to. Some PPC stories suggest that the building is merely labrynthine instead of literally impossible to navigate, and it's apparently much easier for Flowers to find their way around, but it isn't known for sure.
PPC HQ is located, well, everywhere. Some of it is built within plotholes and some of it may be Unplottable, but for the most part, it is made up of tiny fragments of the various worlds. A short stretch of corridor may be inside the Misty Mountains, while the next stretch could be in orbit around Hoth, but most corridors seem to be underground. These are natural plotholes, so in the event of a complete power failure, they will still remain open. Most of these natural plotholes have suspended HQ in a null space between worlds, which contributes to the large number of beasts and beings from all continua dropping into HQ at a much higher rate than they'd drop into anywhere else in the Multiverse.
The original core of HQ was on the Flowers' homeworld of Origin. It expanded off-world via plothole, and massively increased in size when the young Makes-Things set off the plothole-creation event known as the Cascade. The Cascade led to the destruction of Origin and HQ's original complex, leaving the multiverse-spanning plothole network. This massive network is incredibly unstable, due to the interlocking canonical interference of several worlds combined with the inherently improbable nature of plothole-based architecture, and is kept in place largely by a combination of HQ's powerful shielding and not paying attention to the problem.
On Earth, the PPC's official address is in New Caledonia. A small town has sprung up around one of the aboveground entrances, purportedly to service a local mine but in actuality housing a high number of agents' civilian connections (family, mostly), along with agents themselves and other businesses. This town is alternately referred to as a city and as a town, and is hidden by a Somebody Else's Problem field.