Mount Colah is an outer 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. Mount Colah varies in altitude from 68 m to about 206-217m above sea level. History Mount Colah was originally known as Colah - the name first used by naturalist George Caley to describe a koala in a letter to botanist Sir Joseph Banks. When Hornsby became a shire in 1906 the name was changed to Mount Colah. Colah Post Office opened on 29 September 1905 and was renamed Mount Colah in 1906. The Pacific Motorway (Sydney–Newcastle) was built through Mount Colah in 1988 and opened in March 1989. In the process it cut through an old World War II gravel airstrip, and isolated 2 holes of the Asquith Golf Course just to the south. Some World War II building remnants are still visible nearby. Mount Colah was voted "Australia's Best Suburb" through an online poll conducted by Ninemsn in 2010. Population In the 2016 Census, there were 7,095 people in Mount Colah. 70.3% of people were born in Australia. The next most common countries of birth were England 4.7%, India 2.2%, China 2.2% and New Zealand 1.8%. 79.9% of people spoke only English at home. Other languages spoken at home included Mandarin 2.9% and Cantonese 1.4%. The most common responses for religion were No Religion 30.8%, Catholic 23.1% and Anglican 17.4%. Transport The Pacific Highway and Ku-ring-gai Chase Road / Bobbin Head Road are the main arterial roads in Mount Colah. The M1 Motorway (known previously as the Sydney-Newcastle Freeway) runs along the eastern side of the suburb. The M1 has an entrance / exit at Mount Colah towards Sydney. This is the scene of many traffic jams if accidents occur between Mount Colah and Berowra. Mount Colah railway station is on the Main North Line and a regular bus service runs to most parts of