What is your favorite "loop" in gaming?

In many metroidvanias, Zelda dungeons, soulsborne games, etc theres a moment where you think you're traversing deep into an area only to open a door and wind up in an area you've been before. Which moment was the most memorable? It can be because of nostalgia (the first time you ever experienced such a thing) or it genuinely was so intense that it blew your mind.

Mine has to be in Re2 and Hollow Knight. Spoilers below!

In RE2, there is a part where you seemingly leave the station. You're in the jail area and you seemingly think you're at a separate location. After unlocking a few doors you're back in the police station. It turns out the previous area was simply underneath you in the basement.

In HK, my jaw dropped when I found myself back at that mysteriously empty room in King's Station after exploring Kingdom's Edge.

Honorable mention to Ocarina of Time- while not exactly a loop it blew my mind when I returned to the Kakariko Village Graveyard for the Shadow Temple. I'd explored this area so many times and had no clue there was a late-game temple hidden at the back.