Isle of Siptah
The Fractured Citadel map marker
TeleportPlayer -166908.546875 307324.34375 -10122.447266
Inside a building at the southen end of The Fractured Citadel, on the second story, under a domed roof, is a room with one entrance and 4 chests inside. You can freely walk inside, but walking back out you bump into an invisible wall that you have to jump over to get out. Additionally, there are invisible walls blocking access to the 4 chests that have been placed in the room as well.