Wiktionary
datestone
n. (context architecture English) An embedded stone with a date carved into it.
Wikipedia
Datestone
A datestone is typically an embedded stone with the date of engraving and other information carved into it. They are not considered a very reliable source for dating a house, as instances of old houses being destroyed and rebuilt (with the old date stones intact) have been reported.
Specific locations have often been chosen for datestones, viz.
- corbel
- gable stone
- Gatepost: a large upright piece of (usually) granite, usually set at the entrance to a driveway or a field.
- keystone
- lintel