Looks like ZOS added large castle style homes which can be used as guild halls.
One i each alliance ...
https://forums.elderscrollsonline.com/en/di...Comment_3649345
Notable Homes
Daggerfall Overlook, 3,780,000 gold:
Before Daggerfall Castle was built, the kingdom's rulers lived in this imposing manor, now known as Daggerfall Overlook. The keep comes complete with a lower dungeon level.
Ebonheart Chateau, 3,785,000 gold:
A magnificent castle keep, complete with walls, watchtowers, well, fountain, and stable, all dramatically sited on the slopes of an active volcano! It just needs a murder, and then it will be haunted as well.
Serenity Falls Estate, 3,775,000 gold:
Set in a quiet corner of Reaper's March, the rural manor of Serenity Falls deserves its name, with plenty of room for servants and livestock, all behind a handsome wall to keep out the bandits and burglars.
We should be able to come up with 4 million gold for one of those!