Mind how you go!
Be Careful where you perch
Where you walk
And where you wander
This shot was taken in the Catacombs of San Domitillia on Rome’s Appian Way.
The tunnels are vast, running 17km (10.6 miles), and mostly pitch black. Only a small section is lit and open to the public.
Exploring on your own would be rather ill advised – and you’d probably get in trouble with the tour guide.