Used to keep thieves out, or criminals inside, building locks are an essential thing in maintaining power in your location.
You must be inside the chosen building to add a lock to it. When the building lock is finished, the ŝlosilo to it will go to the project initiator's inventaro. A ŝlosilo can be copied, with the use of 10 grams of fero and a fajlilo.
A locked building door cannot be passed without either the right ŝlosilo, or a successful lock-breaking attempt with a levstango.
See also: ŝloso, tenuja ŝloso and veturila ŝloso.