Old Lime Kiln

Ref: HLMP2/033

The old Lime Kiln located along the old Willis’s Road was constructed in the late 19^th Century or very early 20^th Century. It is one of two such kilns located on either side of Gibraltar’s Western and Eastern slopes producing quicklime used in the construction of Gibraltar’s underground reservoirs and water catchments carried out during the late 19^th Century and early 20^th Century.

Almost three quarters of the Rock of Gibraltar is composed of Early Jurassic limestone and dolomites rising up to form Gibraltar’s iconic monolithic promontory comprising of a main ridge and sharp crest with peaks over 400 m above sea level.

The abundance of limestone has been a source of construction material in Gibraltar since the very first city was built in the 12^th Century. The Arab chronicler Ibn-Juzayy described how the white houses of Gibraltar contrasted against the abundant red sands accumulated along Gibraltar’s western slope. Since this time, limestone has been traditionally used as a raw construction material. Therefore, Lime Kilns, which cooked the limestone to make lime, have been around since medieval times for the production of lime mortar for construction purposes.

They were also used extensively in the 18^th and 19^th Centuries, and Gibraltar’s lime kilns date from this time. There were a number of kilns located on different parts of the Rock, but today only the kiln located on Willis’s Road survives. Three types of lime were produced: White lime (used in agriculture), Slaked lime (used as weak building material) and Quicklime (used in construction works).

Limewashed interior of Nuns' Well.

The latter was produced by heating crushed rock up in a kiln. The end product was a very corrosive substance that was used in the old days by the authorities to dispose of bodies quickly. Quicklime was also used to make whitewash which was regularly used to paint houses and patios, a practice that seemingly goes back to the days of the 14^th Century when the Arab chronicler described his view from the Bay. They were also extensively used to paint the inside of cisterns to keep the stored water free from bacteria.

Limestone and lime kilns were an important economic commodity that generated activity in many trades such as stone masonry. The need for lime stone and lime mortar in Gibraltar created a thriving group of trades and industries working with lime, and also a number of related activities such as charcoal vendors who supplied the fuel for the kilns. Lime Kiln Steps in the Upper Town takes its name from the activity of lime production. In the early 18^th Century, a Mr. John Crutchett obtained a monopoly to burn lime for the civilian population from three kilns which operated at the top of the lane leading to his large house and garden. This lane would later be known as Crutchett’s Ramp. In 1776, plagued by ill-health, the house, grounds and kilns were sold by court order to pay off Crutchett’s debts. The lane is colloquially referred to in Gibraltar as La Calera, the Spanish name for a Line Kiln.

Crutchett's Lime Kilns, Road to the Lines.

The size, design and construction material used in the construction of the lime kiln at Willis’s Road suggests that this was a Government rather than private construction. The location of the kiln itself, above of what was colloquially described as the ‘unclimbable fence’ ensured that access to this kiln would have been out of bounds for most unauthorized civilians. The construction of the kiln, limestone blocks encasing a kiln made of heat resistant bricks specially imported from England, suggests that this kiln was specially designed for large-scale industrial use. Yet, judging from the rough design and construction of the exterior stonework it would appear that the kiln was built with the intention of being used as a temporary rather than permanent structure. It was therefore probably built during the late 19^th Century and intended to readily supply large quantities of quicklime to whitewash the large area of rock above the Moorish Castle which had been stripped of vegetation and prepared as a water catchment for the collection of rainwater.

These water catchments fed directly into the two large water tanks built in the vicinity; the 1.25 million gallon Moorish Castle Reservoir and the 151,000 gallon Poca Roca Tank reservoir both of which were also whitewashed to protect against bacteria.

Stone to extract the lime most probably came from the small quarry located just below the kiln or using rock extracted from the Waterworks tunnel complex itself. Railway tracks leading from the kiln are still visible: these would have led directly to the Waterworks itself.

Preparation of east side catchments 1906-09.

In 1903, the Chief Engineer of Gibraltar came up with an even more ambitious plan, to create a massive water catchment along the slopes of the Great Gibraltar Sand Dune on the precipitous east side of the Rock. The water collected from the east side catchments were stored in the four large reservoirs built inside the Rock and known as the Willis’s Road Reservoirs. A fifth reservoir was built in 1914 increasing to twelve by 1961. These reservoirs and tunnel works were also subsequently whitewashed to make them both waterproof and antibacterial. The east side water catchments which consisted of corrugated galvanised iron sheets were also protected in this same manner which gave the east slopes catchments its white, gleaming features. All these works would have required large quantities of quicklime.

To this end, a second lime kiln, similar to the one at Willis’s Road was constructed on the sand slopes just above Catalan Bay village. The temporary nature of both kilns is evidenced by the fact they do not appear as structures in any of Gibraltar’s OS Maps.