The People of Gibraltar
2019 - The 200 Caves of Gibraltar – Part 1

Abbot's Cave (Cueva de los Abades)
Possibly first mentioned by local early 17th century historian Alonso Hernández del Portillo:
Huesos en peñas. Están un poco más adelante junto a la cueva que se dice de los Abades, peñas que tienen pegadas e incorporadas en ellas huesos humanos . . . 
Known today as Abbot's Cave the bones in question were no doubt fossils of some sort. John Drinkwater even finds time to mention them as a curiosity:
Among the natural curiosities of Gibraltar, the petrified bones, found in the cavities of rocks, have greatly attracted the attention of the curious . . .  from the rocks near Rosia Bay . . . great quantities . . . have been collected.
They certainly captured the attention of Thomas James who collected one or two and couldn't quite make out why on earth they were there.

The cave is not on the Nature Reserve cave lists – or indeed anywhere other than on general lists – so I have no idea where one might find it.

Alameda Grotto
Listed everywhere as a cave and often referred to in postcards such as the one below. I’m afraid I have not been able to find anything more about it.

Below the Grotto Postcard

All's Well Cave - Upper All's Well Cave
I am still on shaky ground. But here goes.

The ledge – A view from the west – (1948 – Elisofon)

That extremely precarious ledge that appears on the bottom left of the above photograph has been known as “All’s Well” at least since the 18th century. The Earl of Chatham’s standing orders of 1825 includes the following:
The Sentry, on a person approaching his Post, is to port his arms, and call out, “who comes there?" and, on the person replying, ‘Officer, relief or Inhabitant’ to say, ‘Pass, Officer, Relief or Inhabitant,“ unless required . . . to detain the latter; and to pass the word “ all's well,” every quarter of an hour, in a distinct tone of voice, from right to left.
I am not at all sure for how long Chatham’s instructions prevailed but William Makepeace Thackeray writing during the mid-19th century had this to say about them:
‘All's well,' is very pleasant when sung decently in tune . . . but when you have it shouted all the night through . . . it becomes no more romantic to the hearer than it is to the sandy Connaught-man or the barelegged Highlander who delivers it. 
It was also the soldier on guard at the ledge shown on the photo above who was responsible for initiating the “All’s Wells” calls - something that may have been initiated not by Chatham but by somebody else during the 18th century. Drinkwater, for example, mentions the ledge in his history of the Great Siege which began in 1779:
The same night, two soldiers . . . deserted from Upper All's-well, in the lines : they were sentries at the same post . . . 
And perhaps more to the point:
. . . in the beginning of the late blockade, a party of miners, forming a cave at Upper All’s-well, in the lines, produced several bones that were petrified to the rock . . . 

Both photographs captioned as All’s Well Cave – my guess is that both were taken from inside the upper cave

Ape’s Den Cave
There are several areas on the Rock named Ape’s Den so I must presume the Cave must be close to one of them.

Ape’s Den at the top of the Rock (21st Century – With acknowledgements and thanks to the Gibraltar Tourist Board website)

The cave is listed as being within the Nature Reserve.

Beefsteak Cave
This one is mentioned by Robert Poole in his journal The Beneficent Bee . . etc which was published in 1753 with references to Gibraltar which he visited in 1748. This is what he had to say about it,
From hence (the Nuns’ Well in Windmill Hill) at a little distance more eastward . . .we went to a large hollow cave formed in nature out of the solid rock; in which is placed a table, with a form on each side and it is called the Beef Steak Cave; where it is said a company of gentlemen meet on a Saturday night to regale and divert themselves though it is so far from the town, the way to it so bad, and the place where they come to affording no very agreeable prospect that if others had the same idea of it as I have; it would soon be deserted.

Location of Beefsteak Cave   (2015 - World Heritage nomination document – detail)

Colonel Thomas James who was stationed in Gibraltar more or less at the same time also mentions it - the only cave he does other than St Michael's.
On this plain of Europa (Windmill Hill) is a Moorish bath (Nuns’ Well) on the north of which . . . is the beef-steak Cave
It was also used as a shelter during the Great Siege in the late 18th century as John Drinkwater confirms in his History of the Siege published soon after,
To the left of this bath (The Nuns’ Well) a cave, under Wind Mill Hill, known by the name of Beefsteak cave; which was a common residence for many of the inhabitants, during the late siege.
During WWII Beefsteak Cave was involved indirectly in Operation Tracer. (See Coptic Cave for more details.)

In 2007 it was reviewed in an article in Geogaceta:
Beefsteak Cave is located towards the southern end of the Rock of Gibraltar, along the cliff line between the wave-eroded platforms of Europa and Windmill Hill Flats . . .  he Cave is almost certainly of marine origin . . . within a larger cave system that has since been eroded away.

Europa Flats looking north towards Windmill Hill – The entrance to the cave is somewhere within the red circle  (Late 19th century – J.H. Mann)
The Cave still contains . . .  at least three of these levels contain in situ lithic industry . . . the earliest known recorded Middle Palaeolithic artefacts from Gibraltar. . . this cave would have commanded a strong position above Europa Flats with Windmill Hill Flats in close proximity. Fossil evidence from the area suggests that a diverse community of ungulate herbivores would have inhabited both plains and would have been an accessible food resource for the human inhabitants of the Cave.
 . . . and yet for all its obvious historical and possible archaeological interest the cave is not listed in the 2018 - Heritage and Antiquities Act

Bellman’s Cave 
Named after Captain William Bellman who was stationed in Gibraltar during WWII. The entrance is beside Saint Michael's Road directly beneath the top Cable Car station.

Cable car on its way up to the top (late 20th century

Bell's Backyard Cave
I can’t find anything on this one other than its general location.

Plan showing the location of Bell’s Backyard Cave as “C” (Undated and unattributed)

Bennett's Cave
See Gorham’s Cave Complex

Bennett’s Cave (Gibraltar Museum – adapted detail)