If we understand the term 'lock' to mean any mechanism, regardless of how crude, used to close a door, then locks have been with us since Antiquity. Although antique locks have disappeared with the doors that bore them, a number of bronze keys have been found at the excavation sites at Pompeii and Herculaneum.
The abundance of iron in Gaul would explain why the Gallo-Roman keys discovered there were made of this metal, especially given how talented our ancestors were in working with it.

- Roman spatula key: the openwork plates lift the moving parts of the lock.
- First signum with just the seal.
- Serrated key: evolution of the Laconian key.