Nun's Well is an ancient subterranean water reservoir in Gibraltar, the British Overseas Territory at the southern end of the Iberian Peninsula.

Nun's Well is thought to be of the Moorish period, and represents some of the earliest evidence of the attempts to provide a water supply in Gibraltar.

[1][4][7] It is thought that the name of the cistern originated with the nuns who previously cared for the Shrine of Our Lady of Europe, another historic site at Europa Point.

[7] Nun's Well was described in the second edition of the journal of British officer and military historian John Drinkwater Bethune, A history of the late siege of Gibraltar, published in 1786.

"Prince Edward, the Duke of Kent (2 November 1767 – 23 January 1820), later the father of Queen Victoria, arrived in Gibraltar for the second time in May 1802.

In the mid nineteenth century, Nun's Well was described by Spanish historian Ignacio López de Ayala in his History of Gibraltar, published in 1845.

[18]"To the Eastward, and near the Virgen de Europa, was an admirably constructed Cistern or tank for receiving water; so magnificent and of such noble architecture, that it is difficult to divine whether it was the work of the Moors, or of more ancient times.

Concurrently, an adjacent area which was covered with the strictly protected Gibraltar Sea Lavender (Limonium emarginatum) had rubble dumped upon it.

[21] In October 2011, the council of the Gibraltar Ornithological and Natural History Society declined an invitation for its General Secretary John Cortes to attend the inauguration of the recently restored Europa Point.

The reasons cited included the destruction of the habitat, the flouting of laws relating to the removal of Gibraltar's protected species, and the ignoring of solicited advice on landscaping with salt-resistant native plants.

"[23][24] Caruana's statements were denounced by the GONHS as a "vitriolic attack" and a spokesman indicated that their society was an "apolitical ... independent NGO" (non-governmental organization).