The perimeter of Kowloon is approximately 20 kilometers. I know because I measured it, with my feet, by running around it. In 1860, England and France defeated China in the Second Opium War. Their troops entered Beijing, burned Yuan Ming Yuan, and forced China to sign the Treaty of Beijing. Kowloon, up to Boundary Street, was ceded to England permanently.
Hence Kowloon should only include Tsim Sha Tsui, Yau Ma Tei, Mong Kok, Tai Kok Tsui, Hung Hom To Gwa Wan, and part of Kowloon Tong. Anything north of Boundary Street is really part of the New Territories. Today, I started at Hung Hom, ran along the Tsim Sha Tsui waterfront, rounded West Kowloon, ran through Tai Kok Tsui, turned into the western end of Boundary Street, ran along Boundary Street to the eastern end, then ran as close as possible to the waterfront until I was back in Hung Hom. I can now confirm that the perimeter of Kowloon is approximately 20 kilometres.
I think I have turned into a 量地官.