It’s not difficult to see the appeal of the tiny apartments in Tokyo, which the Economist Intelligence Unit ranks as the world’s most expensive city. But this type of “housing” wasn’t always considered a permanent solution — they started out as cheap hotel rooms for businessmen who stayed out too late working or drinking, reports CNN. Somewhere along the way, people realized the capsules’ roughly $30/night rate was far cheaper than apartment rents, which can top $4,000 a month for a two-bedroom.