Gibraltar, more than an afternoon

A cable car has run from the town centre to the top of the Rock since 1966, and it remains the quickest way to get above Gibraltar's crowded lower streets and into the Upper Rock Nature Reserve, where most of the Barbary macaques spend their days and the views stretch, weather permitting, across the Strait to Morocco. For a port call with limited hours, the cable car does most of the heavy lifting: fifteen minutes or so from the harbour area to the summit station, past several of the Rock's main attractions on the way up. It is worth boarding early rather than late; queues build through the morning as day visitors arrive from the Spanish side of the border, and the light on the Strait is generally clearer before midday than after it.

A cave built for hospitals, and used for concerts instead

St Michael's Cave, one of several hundred caverns inside the limestone Rock, is the largest regularly open to the public, a chamber of stalactites and stalagmites large enough that it was fitted out as an emergency underground hospital during the Second World War, on the assumption that Gibraltar might come under sustained attack. It was never used for that purpose in the end; what it has been used for since is concerts and events, its natural acoustics turning what was built as a wartime contingency into one of the more atmospheric small venues in Europe.

A fortress with more inside it than outside

Gibraltar's defensive tunnels began during the Great Siege of 1779 to 1783, when engineers cut galleries into the Rock to position guns where no attacker could easily reach them, and the network grew enormously during the Second World War, when the garrison excavated an underground complex large enough to have functioned, in principle, as a self-contained town: barracks, a hospital, a bakery and enough storage to keep a full garrison supplied under prolonged siege conditions. A portion of both eras is open to visitors, the Great Siege Tunnels and the wartime galleries reached separately, and walking through either gives a clearer sense of Gibraltar's military priorities across three centuries than the town's more visible fortifications manage on their own.

Back down to Main Street

The upper Rock accounts for most of a day's sightseeing; the town below is worth the remaining hour or two, not for any single monument but for the particular texture of the place, red pillar boxes and pubs alongside Spanish-influenced architecture and a notably international population, a small British town that has never entirely stopped feeling like a frontier post. Duty-free shopping along Main Street draws a steady trade from day visitors and ship's passengers alike, and it is a reasonable place to end a day that began several hundred metres higher up the same Rock. The walk down from the cable car's lower station to the harbour is short enough to manage comfortably on foot, past the Moorish Castle and through the old town gates, which makes it easy to fit the whole circuit, summit to shore, inside a single morning if a ship's schedule demands it.

Gibraltar features on a wide range of itineraries rather than any single type of cruise: Ambassador's Soul Train at Sea and Christmas Sun Escape to Spain and Portugal both call here on routes built mainly around music, warmth or the season, while longer voyages like the Autumn Mediterranean and Iberia Sailing and Mediterranean Moments and Solar Eclipse treat Gibraltar as one stop within a considerably bigger itinerary.

Whichever ship brings you here, a single day is enough to leave Gibraltar feeling properly visited rather than merely glimpsed, provided the cable car is the first stop rather than an afterthought. Leave it until last, as many day visitors do, and the queue alone can eat the hour you had set aside for the summit.