In 1830 the Government erected a windmill on the site of what is now the Obelisk, which provided flour making capacity to Newcastle’s growing population. It became a prominent landmark for sailors approaching the port of Newcastle. In 1847 the windmill was sold by the Government to a Newcastle resident. While this caused a storm of protest, the purchaser demolished the windmill before the contract could be cancelled. Eventually the Government re-acquired the site and the Obelisk was erected in place of the windmill in 1850.
The Obelisk reservoir was built in approximately 1884 as part of the Newcastle permanent water supply scheme, with the land being vested in Hunter Water. It is of concrete construction approximately 14m in diameter and 4 m deep having a capacity of 585,000 litres. It is located underground at the top of a high knoll known as Obelisk Hill. The reservoir was covered with a concrete roof which in turn was covered with earth and grass. Obelisk Hill is now a popular park and lookout with expansive views.
The Obelisk has suffered damage at various times from lightning strikes and was seriously damaged during the 1989 earthquake. Disaster struck on June 8 1985 when the reservoir buried beneath the Obelisk exploded, causing its roof to collapse and injuring two young girls.
The explosion was heard across Newcastle and an inquiry was undertaken. The inquiry found that the explosion was caused as a result of gas leaking into the reservoir from a damaged gas main. The gas was ignited by sparks from fireworks that the victims were using. After the explosion the reservoir was filled in and a plaque was laid to mark the event.