In 1884 the custody of the ancient Roman cistern was given to the local council of Albano by the Abbot Commendatario of Badia of St. Paul, Monsignor Tancredi Fausti. The minutes for the 16 March 1908 recount: 'The pool of the Praetorian camp, a huge reserve of water exceeding ten thousand cubic metres of water, which is found inside the area inhabited by the Praetorians, abandoned for centuries and full of earth and rocks, now cleaned out, repaired and returned to its original use and donated to the community by the abbot of St. Paul's Monsignor Tancredi Fausti, in return for the right to take a certain amount of the water. The cistern was cleaned out and put back into use under the mayor of Albano, Pietro Feoli, at the expense of the town who used it as a supply of drinking water originating from springs on the slopes of Nemi. The cistern was constructed on the highest part of the hill, so that it could supply all the habitations underneath it. The architect made use of a natural strata of solid rock creating an irregular rectangle which was divided into five longitudinal naves, which are distinguished by huge pillars. These pillars themselves are part of the solid rock, the surrounding space having been hewn out, and they were then extended in height using brickwork to create arches that thus connected each pillar to the next. The naves were covered in vaulting in round arches, and the roof finally covered with tiles of tufo and cement (malta compatta?). The walls were constructed in a rectangular form, using courses of bricks. The walls and the floor of the cistern were finished with 'signino' and some holes 60cm long were made in the vaulting for ventilation. A stairway of 31 steps was constructed to allow access and inspection of the cistern. The surface area of the cistern is 1,436.5 sq. metres and its capacity 10,132 cubic metres of water (Lugli p.251) There are two water sources that supply the cistern: the Malaffitto and the Pescaccio, the older one issued above the cistern and the other one on the lower wall, later confined by a channelling aqueduct constructed also in the Roman period. The dating of the construction, from the technical methods used, from the liberal use of unrefined cement, from the use of blocks of tufo of varying size, is certainly to be put at the beginning of the III cent. and more precisely between 202 and 203 A.D., after the arrival of the Legion at Albano and on the 10th anniversary of Septimius Severus' coming to power (Calderini p.76, Passerini p. 550, Levi p. 414).
The construction of this important water supply was part of a complex of works carried out by the II Parthian Legion, for the use of the military camp. The soldiers decided on the positioning of the cistern in its present site due to the homogeneity of the underlying rock (tufo) and its altitude, thus able to distribute its huge capacity to various secondary cisterns.
In 1912 the cistern was emptied and cleaned as the purity of the water had been compromised due to the bad state of repair of the conduits and aquaducts. On the occasion a detailed study was carried out by the untiring efforts of Prof. G. Lugli, who carried out one of the most scientific studies of the site and which today is indispensible for a knowledge and dating of the hydrological system. The rubbish and mud extracted from the bottom of the cistern was deposited around the site on top of that already deposited in 1884. Thus the difference in height with respect to the ancient access stair was accentuated. Research and studies on the monument had been carried out in previous centuries, when the gardens of the Badia of St. Paul which belonged first of all to the Girolamini monks and later to the "Apostolic Camera", were the subject of investigations during research into the ancient ruins of the amphitheatre and the Roman cistern.
Fascinated by the 'pool', even though largely obstructed (as shown in the plans of Piranesi), scholars and artists of the past drew it and described it: Archive documents that deal with the area where the cistern is situated, describe it, from the medieval period onwards, as a vegetable plot adjacent to the garden of Badia of St. Paul. The deed, dated 21 October 1282, with the seal of Giacomo Savelli, who became pontiff with the name of Onorio IV, witnesses the gift made by Cardinal Savelli to the Sacred Religious Order of the Monks of St.William. For about two centuries the monks looked after the monument, using the water for their own needs; in 1445, by order of the Camerlengato of the Holy Roman Church, the Monastery and its surrounding holdings were abandoned by the monks. The Cardinal Camerlengo of the Holy Roman Church Ludovico Mezzarota Scarampi, was the first Abate Commendatario of the the Monastery of St. Paul and had the great honour to look after the whole property. During the trip by Pope Pio II Piccolomini to the Colli Albani and in particular to the Badia of St Paul, which took place in May 1463, the pontiff's praise for the work that had been carried out was fullsome. In book XI of the Commentaries we read: The Cardinal Camerlengo Trevisano, was given the benefice of the Monastery of St. Paul in the upper neighbourhood of Albano Laziale. Since it was by then in a ruined condition, the cardinal wanted to repair the damage. He reconstructed the church that had for some time been without a roof, and put in order the gardens and vegetable plots and made the whole area pleasant amenable. "A spring flows there but nevertheless cisterns were added from which one can draw crystalline pure water (here reference is being made undoubtedly to the Roman Cistern, that was still functioning at that time, ensuring the supply of water to the whole community of Albano). The air there is pure and healthy, although the place is, by virtue of its position, exposed to the winds that blow from Africa." (F. Petruccci, p. 77)
In December 1492, at the request of the Commendatario Giacomo Savelli, a new bull was promulgated by Alessandro VI (the then Pope and previously bishop of Albano and ex-abbot Commendatario of the Badia of St. Paul) which entrusted the running of the property to the Monaci Girolamini of St. Alessio in Rome. The greatest neglect and ruin of the 'cisternone romano' took place during the 17th, 18th and 19th centuries, in which time the antique aqueducts were diverted and broken due to a lack of maintainance and lack of water, as witnessed to by the civil engineer for the area, M. Salustri: Report on the drinking water, originating from the springs of Palazzolo, of the Comune of Albano........on the state of the aqueduct and the repair work carried out. In this report, which covers a period from 1607 to 1921, the work carried out by the Savelli princes and most of all, by Cardinal Benedetto Pamphili who, in Sept. 1708 financed the repair and cleaning up of the aquedect Malaffitto is described. This work by the cardinal was made as a gift to the community of Albano. During the fifty years of the French Occupation the Badia and the property pertaining to it underwent a notable decline with the vegetable plots and the garden being filled with brushwood and rubbish. On the 17th March 1821, the Order of the 'Monaci Girolamini' being extinct, the monastery finally entered into the possession of the Missionary Fathers of the Most Precious Blood. From 1884 the ancient 'reserve of water' and the surrounding land has been entrusted to the care of the Municipality of Albano that has provided for its care and maintainance and who still use it today for the irrigation of the fields. At the present time the local council is about to develop the monument with the addition of floating structures to enable visits by the public, proposed Dr. P Chiarucci, curator of the museum at Albano. Putting in order the area surrounding the site has been entrusted to an Albano architect, Marco Dalle Selve, who has proposed leisure spaces set up and furnished for the study of the monument, with explanatory drawings engraved into the stonework. The area will be provided with a sundial of classical design.