The oldest surviving building in Queensland, the Windmill, was constructed by convicts in 1828 to grind flour and maize meal as food for the Moreton Bay Penal Settlement. A stone and brick building, it contained two pair of mill stones - one pair connected to the Windmill sails, the other to a treadmill outside. The treadmill was used when the Windmill was under repair, in calm weather, or as a means of punishment for convicts. It was demolished after the area was opened up to free settlement in 1842.
The Windmill fell into disuse, and was converted to a signal station in 1861. It was also used as a fire look-out, and for pioneer radio and television broadcasting experiments in the 1920's - 1940's. The extant copper time-ball was dropped regularly from 1895 to 1930 at 1 p.m.
Of the adjacent Reservoirs, the smaller was built in 1871 in association with the Enoggera Dam Water Supply Works. This was the first major municipal engineering undertaking in Queensland, servicing Queen, George and Edward Streets. The second larger structure was completed in 1882.
The Reservoirs are brick, box-form structures with subterranean, arched, baffle walls. The timber and corrugated iron roofs are later additions.