Devil's Gap Road (AKA Referendum Steps or Escalera del Monte in Spanish and Llanito) is a pedestrian street with painted steps in Gibraltar's Upper Town district. The steps climb from Flat Bastion Road to the start of Devil's Gap Footpath and Baca's Passage. It is the quickest walking route from the city centre to the Upper Rock Nature Reserve.
The Union Flag and Queen Elizabeth's royal cypther, EIIR, are painted onto the steps. They were originally painted by residents during the build up to Gibraltar's first sovereignty referendum held on 10 September 1967, when Gibraltarians first rejected Spanish sovereignty. The steps were last repainted in August 2011 by a group of youngsters following a Facebook campaign called "Repainting Our History".
The cache is actually located in Baca's Passage but I think Devil's Gap Road is the perfect starting point and makes for an interesting walk. Look out for more faded 1967 artwork on the walls leading to the cache.
This is also a good starting point if you're planning on walking up the Rock to log the many geocaches hidden within the nature reserve.