The Noon Gun fires from a small battery on the lower slopes of Signal Hill, audible across the entire central bowl of Cape Town. It has gone off daily — Mondays to Saturdays — since 1806, making it almost certainly the longest-running daily time signal anywhere.
The battery itself is open to visitors. Arrive a few minutes before noon to watch the loading and firing; the navy gunners are friendly and happy to explain the procedure. The walk up from the Bo-Kaap is steep but short, and the view back over the city as you wait for the gun is a small reward in itself.