Rim Locks and Rim Latches
Rim Locks and Latches have been used for centuries to lock and latch doors. They sit on the surface of the door rather than set into the edge of the door, traditionally because the door would not have been thick enough to take a mortice lock or latch. They therefore have a strong visual presence and will add instant character to any setting. A rim lock or latch requires a special type of door knob (a "rim" knob) that you will need to purchase separately. You can browse rim knobs here.