Terrain, buildings, and everything underground that exists in an open source. The purple routes are reconstructions, anchored to surveyed portals but not surveyed themselves — click any of them to see exactly what holds it in place.
Depths are the weak point, not the positions. Road tunnels are drawn on a straight grade between their portals. Located sites are drawn at the surface point that is actually recorded, because no open source gives their depth. Click anything to see which applies.
A free map of Gibraltar's terrain and buildings, and of everything underground that exists in an open source: tunnels, galleries, batteries, magazines, caves and heritage sites. You can cut the Rock open, switch to x-ray, and click anything to see what it is and where the information came from.
Gibraltar's military tunnel network runs to roughly 55 km. About an eighth of it exists in open, georeferenced data, and that is what is here: the Great Siege galleries on the north face, the WWII arteries including the Great North Road, Foss Way and Maunsell's Winze, 98 surveyed tunnel entrances taken from a 1:5,000 survey sheet, and over 1,100 named places. Depths are the weak point, not positions — every feature says whether its elevation is surveyed, published, estimated, or unknown.
Sources. Terrain, 2013 aerial imagery and 13,538 building footprints from the HM Government of Gibraltar geoportal; elevation from Spanish IGN PNOA-LiDAR (CC BY 4.0, scne.es); tunnel centrelines from OpenStreetMap (ODbL); listed sites and memorial plaques from the Ministry for Heritage register; 634 defence works from the Fortress of Gibraltar Group's gazetteer. Machine-readable summary: llms.txt and data-sources.json.
Also here: Where can I park in Gibraltar? — a companion map of every parking bay.