We were not aware, prior to this point, that the Rock of Gibraltar consists of Jurassic limestone. It contains many tunnelled roads, most of which are still operated by the military and closed to the general public. Gibraltar has 29 km of public roads, not even enough for a marathon. The tunnel system through the territory is considerably longer than the total road system itself.
When we reached the entrance to St. Michael's Cave we were greeted by some of the most important and protected residents of the territory.
There are roughly 230 Barbary macaques living on Gibraltar. They most likely were brought here by the Moors early in their conquest of the Iberian Penisula. During WWII, their population diminished and it was said that, if they were ever to disappear from the colony, Gibraltar would fall to the enemy.
But I digress...