"The Johore Battery is a gun emplacement site that consists of a labyrinth of tunnels that was used to store ammunition to support three monster guns that could fire 15-inch shells.
Built by the British in 1939 for the defence of Singapore, the guns were the largest installed outside Britain during WWII. The guns were destroyed before the surrender of the British army and the tunnels were sealed up after the war. Their location remained a secret until the Singapore Prisons Department rediscovered them in April 1991.
Today a replica of the monster gun and 15-inch shell sit at the Johore Battery and visitors are able to view the original tunnels through a reverse periscope at ground level. The dept of the tunnels can be experienced through an echo tube."
Hmm...more tunnels....too bad they are sealed up...like the labrador park ones....