Mount Colah is a suburb of northern Sydney, in
the state of New South Wales, Australia 29
kilometres north of the Sydney central business
district, in the local government area of Hornsby
Shire.

Mount Colah is 5 km north of Hornsby, the nearest
major town centre. It is one of the
most northerly suburbs of Sydney and is where the
"Welcome to Sydney" sign is located. Mount Colah
is the second highest suburb in Sydney by
elevation.
Considered one of Sydney's leafier suburbs,
streets are clustered around the Pacific Highway.
Mount Colah is bordered to the east by the
Ku-ring-gai Chase National Park.