Governor O'Hara did not approve of St Vincent's plan as he proposed to finance it by selling the naval stores at Waterport and Irish Town.

Construction of the Rosia Water Tanks began in 1799 and was completed in 1804 by the contractor Giovanni Maria Boschetti.

It formed part of the Royal Navy base and contained stores of food, water, and clothing in sufficient quantities for a large fleet.

The Rosia Mole was the berthing place for the Royal Navy vessels seeking provisions and water from the Victualling Yard complex; it also held coal for the garrison.

[3][5] Having taken ownership, the Gibraltar government demolished the unique underground water tanks in 2006, in the face of international opposition.