The British took over Gibraltar in 1704 and were under intermittent siege from the Spanish and French so they built high thick walls around the city from stone cut from the Rock. The main sights included St Michaels cave, a large cavern in the centre with the usual stalagtites and stalagmites (not well cared for) and some lower caves leading to a lake; Apes Den is near the top of the cable car and is where the Macaques (tailess monkeys) are fed 4 times a day so are plentiful and friendly. The Great Siege tunnels initially built by hand at the start in 1782 to get cannnon lined up to fire into Spain from halfway up the rock face. By the end of WW2 there were 50 km of tunnels.
Nowadays everyone can walk across from Spain, crossing the airport runway by foot or car.
Nowadays everyone can walk across from Spain, crossing the airport runway by foot or car.