Ever since I was a kid I've been curious to know what lies beneath holes like these. When I was young I remember playing in stormwater pipes not far from my parents' home. I remember walking below the streets watching people pass by from beneath the drains in the road. Fortunately for my brother, sister and friends we had sense enough not to play in the tunnels when rain was imminent, but still, I sometimes shudder at the danger we put ourselves in. Not only was there the possibility of being trapped by some kind of freakish flood, but there could have easily been freakish people wandering the tunnels too.
A few years after leaving home, I noticed that the municipality had erected heavy iron grids in front of the entrances. I do hope this was in response to residents' complaints, and not as a result of some unfortunate incident. To be honest however, I suspect it was because the cops got tired of chasing baddies down the tunnels! :)