Nicholas Borge: Impressive. Also arrange a tour to "lower St.Michael's" which has an underground lake, though you have to be fit http://www.visitgibraltar.gi/see-and-do/natural-attractions/lower-st-michaels-cave-36
Nicholas Borge: Got to be done. You can take a cable car up, or have it as a mid-point stop on your Upper Rock tour. I'd recommend a walking tour if you can, as you can go at your own pace.