The Noon Gun, as you might guess from the name, is a signal gun fired every day at noon in Cape Town. The gun is perched atop Signal Hill, not far from the city center, and it has been marking the time since 1806. The two cannons (one is a back-up) on the hill date from the late 18th century, brought on a British ship and once used in warfare. The firing of the gun at noon was meant to give ships in the harbor a chance to synchronize their chronometers.
Even after the gun was no longer needed to establish chronometer accuracy, it was still fired each day at exactly noon – as it still is today. The only days the Noon Gun does not fire are Sundays and public holidays.
The Noon Gun is on Signal Hill, which is reached via Military Road in the historic Bo-Kaap neighborhood. It's open 24 hours a day, and is free to visit.