If you've just found the Imbued Sword Key in Elden Ring: Shadow of the Erdtree, your first thought was probably "Oh hells, not this again" followed shortly after by wondering where to find the Belfry you can use the key. For those familiar with the base game, Elden Ring has a location called the Four Belfries in Liurnia that lets you use Imbued Sword Keys to open portals.
These send you to self-contained mystery locations all over the map, and are a fun way to get a sneak peak of what the game still has in store.