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, or may in some cases be the date of a renovation or alteration.
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
See also Marriage stone Cornerstone
References
External links Scotland's Marriage and Date Stones The Societe-jersiaise An essay on datestones (mostly in London)