Coordinates: 51°21′45″N 0°01′38″E / 51.3625°N 0.0271°E / 51.3625; 0.0271
Keston is a part suburban, part rural area of Greater London within the London Borough of Bromley, England. It lies on the edge of Hayes Common, to the northwest of Greater London's border with Kent.
Flint implements and pit dwellings on Keston and Hayes Commons show occupation of the area back to at least 3000 B.C., and there are Iron Age encampments in Holwood Park and on Keston Common.
In the valley below the village are the ruins of a complex of 3rd century AD Roman tombs and mausolea (51°21′04″N 0°01′48″E / 51.3511068°N 0.0299549°E / 51.3511068; 0.0299549) connected with the nearby 1st - 4th century AD Roman villa excavated 1967-1992 (51°21′02″N 0°01′44″E / 51.3506679°N 0.0287962°E / 51.3506679; 0.0287962).
Sited closer to the original Keston Court than the main village itself, Keston's small medieval church is unusual in that does not have a dedication to a saint, but built into the altar-table is the top of the 17th century altar inlaid with a very elaborate cross and inscribed "The Keston Marke: IN HOC SIGNO VINCES", so the parish has a distinctive symbol instead.