The fictional Wapsi Square neighborhood of Minneapolis is approximately located by reference to real-world landmarks. Lake Calhoun has been a frequent fixture throughout the strip's run, and other locations shown or mentioned put Wapsi Square to the east of the lake and southwest of downtown - in or near the real Whittier neighborhood. The name derives from the Wapsipinicon River, which is not actually near Minneapolis.
The Bibliothiki or The One Library is an extradimensional library, magical and somewhat self-directed; it gets a copy of every written work made. Phix has been the librarian for quite a long time, and she's recently been joined by Nudge. Do not annoy the staff. It has a "no humans" rule which is poorly enforced; most patrons are supernatural folks like Euryale and Brandi.
A nightclub, apparently somewhere in downtown Minneapolis; it's unclear if its clientele is specifically slanted to the supernatural set or if we're just lucky. This is where Jin first met Alan.
A restaurant at the corner of W Lake St and Hennepin, with an alley in back. In Wapsi Square here is a portal to the Bibliothiki in the alley behind it for authorized visitors. In the real world one may observe the restaurant, if not the dimensional gate.
Never actually depicted in the comic, the Demon Realm is variously described as 'timeless' or 'outside time' - whatever that means, demons have views of time that don't match up to those of humans. Mayahuel was trapped there for an extended period during the time loops, and only recently returned to Earth. For a brief period (as Earth measures things) travel between the realms was possible; it's now much more difficult.
The most often mentioned real-world location, quite close to the Wapsi Square neighborhood. Most outdoor recreation in strip happens there. This is where Monica went bicycling, where Bud tried to rollerblade, where Bud streaked a news crew, where Katherine goes out with her fish Oscar, etc.
After the sandbar was blown up in the U-296 incident, Monica and Jin went exploring and found another uninhabited tropical beach...eventually. It's accessible via Bibliothiki teleporter as well as direct poit-ing and many of the characters have enjoyed it. Its geographic location is unspecified.
Tina's coffee shop, and the best place in Wapsi Square to get coffee or demonically insightful advice. We also see Becky there, providing pastries or filling in at the counter. It's on the way between Monica's house and the museu, a few blocks east of Bud & Brandi's apartment, and within walking distance of the intersection of Lake & Hennepin. Tina owns the building but does not live on site; there is a basement but apparently no attached apartment.
There is apparently a second interesting coffee shop in the area, where the satyr siblings Jacob and Randi work, but we don't yet know how close it is to Mucho Mocha.
Monica worked for years at a Minneapolis museum, along with her boss Gregory Fields and coworker Katherine Gilchrist. Another co-worker was Janet, who didn't appear much in this time line but who has been Monica's friend in previous time loops. Some other staff members have shown up and a few were named, such as Mike the security guard; presumably there are many we've never seen. Monica's office was down in the basement along with Katherine's; Dr. Fields has one on the ground floor. This is where she first met Kevin and Tepoz. The museum is not too far from Mucho Mocha.
Monica's museum office was in the basement, next to a storage room and having piping along one wall. It's not particularly near Katherine's office, which is near the storage room with the office supplies.
Not seen recently, this is the yoga studio Jacqui opened. Her assistant Luci had trouble getting along with Shelly for a while, and vice versa. Shelly designed the sound system and now works there as a personal trainer. "Punk Yoga: No posers. Just poses."
A sand bar in a shallow part of the ocean, somewhere in the Bermuda Triangle, which was used as a warm getaway area by the teleporting characters and their friends. It was destroyed when Bud accidentally blew it up. After the U-296 incident they've found another isolated location known only as Monica's Island.
In reality, an enormous archaeological site near Mexico City the remains of a city that reached its height about 450 AD; in Wapsi Square, it's also where the Calendar Machine was hidden. The name may mean "birthplace of the gods" or "place of those who have the road of the gods," and its early history is unclear. A number of dieties were worshiped there, including at least two serpent gods (although Kukulkan got popular later), the god of pulque and a "netted jaguar."