The Romans used several types of locks for doors: the Laconian or primitive wooden pin tumbler lock, the padlock and the built-in or fastened-on metal lock. There are no locks in this collection that I can definitely identify as door locks. However, it seems that some of the larger barrel locks were used on doors, replacing the more primitive wooden locks. For example, the formidable 500 page volume on Roman antiquities in the British Museum (Guide to the Exhibition) has this to say about them: "Padlocks of Roman date are common. In this Case three of a barrel form are shown. One (No.400; fig. 173. has the key still rusted in it. The padlock has traces of a chain attachment at one end, and was probably kept hanging to a door post, while the bolt was shot into the end link of a chain attached to the door." Of course, such an arrangement would not allow the door to be locked from the inside, so bars must also have been used.

 The image at right shows a barrel lock found at Lullingstone Roman Villa (Flikr). It is virtually intact and is evidently to be mounted on a surface such as a door. It would require the "bolt" to be drawn completely out of the lock when released by the key. The lock body itself would be fastened to the surface.

As evidence of the metal door lock I first show here the two illustrations by Stender

Figures 3 and 5  below)(archeologie-Krefeld.de/Bilder). These are images taken from a Roman sarcophagus, showing a model of a metal pin tumbler lock. This is now in the Deutsche Schloss-und Beschlagemuseum at Velbert.

Door lock, Pompeii This is the image of a door lock with a mechanism for a rotary key. This was found at Pompeii in the so-called "House of the Locksmith" (Towne) attached to the wood plank and with the key in place.

Barrel Lock  Next is a nearly complete barrel lock from Lullingstone (flikr/finkangel) which has a strip of metal attached that was obviously meant for mounting on a wood surface. I believe this to be a door lock.

Hoyuk A and B  Front and back of a Byzantine surface lock, thought from context to be from a stable (300-1100 CE) (Gorny)

Quennell ring key and lock.  I'm repeating this sketch because it is a rare image of the operation of a lock for a rotary key. It could have been used either for a door or a chest.

Door Lock, turning key  Compare this functional diagram by Raine (historicallocks) to that of Quennell.  I think they are both showing the same basic mechanism, slightly different interpretation. However, I have never seen any surviving bolts that would serve in such a device. There must have been a very large number of them.