The Royal Ice Factory’s Freezing Tanks

This set of 44 freezing tanks with a depth of 30 centimeters, arranged in ingeniously designed terraces, has remained intact until the present day.

These are individual but intercommunicating units, through which the water circulated through a system of gutters and holes, located at the base of the separation walls, filling each one in turn, in a cascade.

During the cold winter nights in the mountains, the water in the tanks froze, forming thin sheets of ice: the so-called “caramel”.

In this structure, circulation zones were also delimited between rows of tanks, for access by workers who collected ice that had already formed.

It is not possible to make a reliable estimate of the annual production of ice during the period of full operation of the factory, but it is estimated that around 66,408 m3 of ice were produced.

Entre 1741 e 1886, houve transformações significativas e foram implantadas novas estruturas no complexo da Real Fábrica de Gelo. Assim se explica o aumento da área ocupada pelos tanques de congelação, por exemplo: aquando da construção, já em meados do século XX, do complexo militar vizinho, terão sido destruídos tanques de congelação e pelo menos um grande depósito.

As sondagens arqueológicas realizadas entre 1993 e 1995, junto ao depósito e aos poços existentes, puseram a descoberto o que poderá ter sido uma estrutura de apoio ao abastecimento de água. Esta descoberta permitiu identificar uma parte da fábrica anterior à fase de reedificação (1782).