Woolsthorpe-by-Colsterworth is a hamlet in the parish of Colsterworth, in the English county of Lincolnshire, best known as the birthplace of the scientist, philosopher, alchemist, and mathematician Sir Isaac Newton. It is not to be confused with the village of Woolsthorpe-by-Belvoir, generally known just as Woolsthorpe, which is also in Lincolnshire but about 8 miles (13 kilometres) to the north-west.

Woolsthorpe-by-Colsterworth is 100 miles (170 km) north of London, and 1 mile (2 km) west of the A1 (a major road once called the Great North Road). It is close to the borders with the counties of Leicestershire and Rutland.

External link