Nyandarua County is a
County in the former
Central Province of Kenya. Its capital and largest town is
Ol Kalou. Formerly the capital was
Nyahururu, which is now part of the
Laikipia County. Nyandarua County has population of 596,268 and an area of 3,304 km². The county is located on the northwestern part of the old Central Province, and contains the
Aberdare Ranges.