[4] The reserve was established in 1993[2] to protect the area of land that the United Kingdom's Ministry of Defence had decommissioned from military use.

Its purpose is to preserve the wildlife and natural and historical sites, while providing access to the public.

The protected area now covers the Great Gibraltar Sand Dune, Windmill Hill and the Europa Foreshore.

[8] The Gibraltar Heritage Trust manages conservation of the historical sites and their development as tourist attractions.

[11] The passage of George's Bottom Cave is tight, requiring crawling at some points, including the entrance.

[11] Crawling is made no easier by the cave coral which together with the curtains, columns, straws, and helictites create a variety of formations.

[5] The maquis, or dense Mediterranean scrub, is mostly made up of tall bushes that include wild olive, Mediterranean buckthorn, lentisc, Osyris and terebinth, and smaller bushes that include shrubby scorpion vetch, spiny broom, teline, wild jasmine, shrubby germander and felty germander.

Understory plants include the intermediate periwinkle, Butcher’s broom, Italian arum and Bear's breech.

The firebreaks in the maquis are home to plants such as paper-white narcissus, common asphodel, giant Tangier fennel, wild gladiolus, Galactites and mallow bindweed.

[13] There are small areas of garrigue in the reserve, low scrub that includes wild rosemary, esparto grass, white asparagus, toothed lavender, cut-leaved lavender, teline, Prasium, shrubby scorpion vetch and germanders.

[13] The many cliffs around the reserve harbor joint pine, dwarf fan palm, sweet alison, Biscutella and wild parsley.

[1] Gibraltar has a reintroduced population of Barbary macaques, the only wild primate species in Europe, the famous Rock apes.

[19] The Rock of Gibraltar, at the head of the Strait, is a prominent headland, which accumulates migrating birds during the passage periods.

The vegetation on the Rock, unique in southern Iberia, provides a temporary home for many species of migratory birds that stop to rest and feed before continuing migration for their crossing over the sea and desert.

[citation needed] The Rock has been identified as an Important Bird Area by BirdLife International because it is a migratory bottleneck, or choke point, for an estimated 250,000 raptors that cross the Strait annually, and because it supports breeding populations of Barbary partridges and lesser kestrels.

33 species of butterfly have been observed, including the Cleopatra, two-tailed pasha, swallowtail, Spanish festoon and striped grayling.