Castle Hill is a picturesque suburb, possibly named beacause of the views from the hilly areas in the district. It was fist seen by Governor Phillip on one of his trips of exploration in 1791. An official post office opened in the hills district in January 1869, and the public school took its first pupils in July 1880. In 1926 electricty came to Castle Hill.

The first stage of Castle Towers which continued on from 1982,1989,1989,1993,1994 and 2001.

Castle Hill is located 31km North-West of Sydney, and is by far the most famous suburb in the hills. Castle Hill is one of the largest suburbs in population, making up more than 22% of the total population in the Baulkham Hills Shire. Castle Hill alone has a population of 31,9699 people.

Castle Hill is home to Castle Towers shopping centre, Australia's No.1 Shopping centre in 1997, 1998 and 1999. Castle Towers is alone one of the largest shopping centres in Australia due to recent expansion. Castle Hill also comprises a large trading zone which incorporates a number of businesses ranging form car dealers to smash repairs to homewares to banks. The Trading Zone is also the home of Amway.

Castle Hill is home to the Castle Hill show which is on every March at Castle Hill Showground, located in Carrington Rd next to Baulkham Hills Shire Council and The Hills Entertainment Centre.

It is also home to The Orange Blossom Festival Street Parade which is on every September for the past 31 years. The Orange Blossom Festival is a major community festival operating every year, lasting three weeks in September, with opening and closing ceremonies, and including many events in between.