Zero
The location of Haven Zero is a timeline called Zero that has a completely empty Earth, where it was originally believed that humans never evolved, although it was eventually discovered via looking at sites with known human remains that it did have them at some point. Humans appear to have died out about 930,000 years ago, at the same time that all other timelines experienced a major population narrowing. Apparently on Zero it narrowed too much.
Timeline Zero was apparently discovered independently by all the Major Temporal Powers, and when they decided to reduce hostilities, they created entity called Project Zero to create a city called Haven Zero (Commonly just ‘Haven’), for temporal refugees who can no longer survive in an other timeline without being erased by that timeline correcting itself. This city is
Haven’s population is approximately 4000 residents, or at least roughly that many are on the books although Haven notable has a problem keeping track of deaths.
Slightly over 100 contemps (People who are not refugees and still exist at their original place in another timeline) a year currently commute in to work for Project Zero each day, and Project Zero employs approximately three times that many residents.