The Lobby
The mysterious entity known as the Concierge inhabits the strange plane of existence known as "The Lobby". It appears to be a fancy hotel with doors leading to random other parallel dimensions, timelines, and planes of existence. All manner of people's and beings inhabit the hotel, some working as staff on behalf of the Concierge and others waiting their turn to be directed to their return home. There is even a bar, restaurant, repair shop, and spa/gym with strange dishes and gizmos and gadgets to accommodate nearly any known sapient creature. The majority of the rooms are built large enough to accommodate giants and the architecture's trimming and piping are designed small enough to accommodate gnomes, sprites, and other very small beings.