Originally named Rock Island, this small fort housed criminals convicted of petty offences within the colony. It has a dark and mysterious past; rumour has it that a convicted murderer, Francis Morgan, was once hung and left to rot on the island. Fort Denison was fortified during the Russian scare of 1875, which never eventuated. Built from 8,000 tonnes of sandstone quarried near Kurraba Point, Neutral Bay, it was named after Sir William Denison, then Governor of New South Wales. By the time the fort was completed, it was redundant. Fort Denison was included as part of the defence of Sydney whereby the fort's cannon were fired at 1pm each day to help mariners set their chronometers. Today it is fired not for defence purposes but to signal the hour - 1 o'clock