It is also the site of a number of historical buildings including the historic Sydney Observatory (thus often referred to as Observatory Hill), the Signal Station, the remains of Fort Philip, the National Trust Centre (formerly Fort Street High School) and a rotunda which is used for weddings.

The powder magazine was moved to Goat Island in 1833, and Fort Philip was partially demolished in the 1850s.

Although Fort Street School still exists on Observatory Hill the historic military hospital is now the headquarters of the National Trust and several rooms are available to hire as a venue.

Construction ceased in 1806 and at this stage a report on the progress was given by the Colonial Secretary William Minchin.

He said The Fort was originally intended to suppress a possible insurrection by the Irish rebels who had been transported to Australia after the 1798 Rebellion in Ireland.

[6] This was replaced in 1847 by the more substantial stone building designed by architect Mortimer Lewis which exists today.

In 1912 The Sun newspaper interviewed the resident signal master Jeremiah McCarthy and the article provides a colourful insight into the daily activities of the station.

It stated:[7] Jeremiah McCarthy had been appointed to the post of signal master in 1902 and he remained in this position until his death in 1920.

He had also been a light house keeper on South Solitary Island and Smoky Cape for several years before this appointment.

[8] The Powerhouse Museum explains how the Time Ball works in the following terms:[8] The longest serving Government Astronomer to occupy the Observatory was Henry Chamberlain Russell who held this position from 1870 until his death in 1907.

The stones in the structure are over 200 years old as they came from a building at Circular Quay built in the time of Governor Macquarie.

[11] The unveiling was conducted by Major General Sir Charles Cox who at that time was 77 years old and needed to lean on a friend’s arm.

However at the time of the Boer War in 1899 he was a young Officer who led the New South Wales Mounted Rifles.

The gun near the structure was captured from the Boers by the British at the time of the war and given to the Australian Government in 1905.

[12] It is a 75 mm QF (Schnellfeuer-Feldkanone L/24) and was originally in the Botanic Gardens but the Veterans of the War requested that it be moved to their Memorial.