You live/travel in Japan. One day you received an invitation to a country bathhouse by mail. It was a huge sauna with a large assortment. The invitation said that everything is included and free for you.

The bathhouse was not far from Kyoto. You arrived there and went to the bathhouse. No one and nothing could be heard from there, but everything worked. You went inside and looked around. There was no one around. The door closed behind you by itself.