Various documents dated from 1062 to 1102 give the first indications of a tower situated at the dividing point of the waters that flow around the city. It was called the Turlonga (Long Tower), and was almost certainly built between the 9th and 10th centuries, as the cardinal point of the defences, but also as a symbol of the bishop's power over the city. A 16th century tradition held that Ezzelino da Romano constructed two towers, a large western one and a smaller one to the east, called the Zilie, from the name of the architect-builder Zilio, and that both towers were to serve as horrendous prisons for those opposing his regime. The two turreted towers, painted in red and white checks, are seen in the frescos that Giusto de'Menabuoi painted in 1382, for the Conti Chapel in the Church of St. Anthony. The actual builder of the two towers is unknown and the larger of the two, the Torlonga, was actually raised from a smaller watch-tower of the 10th-11th centuries. Stratigraphic investigations show that the lower part of what is now called the Specola, to a height of nine metres, is composed of the three-metre thick walls of the older tower. The raised part with crenulations and holes, for dropping oil or objects, dates to the Carraresi period. The archaeological investigations also revealed the presence of a second fortification that followed along the shore of the river. This is a keep, visible in Giusto's fresco, which predates the construction of the city walls. It was a sort of wall that protected the north and east sides of the Torlonga, where the river did not offer protection. Restoration work in the 1980s and 1990s brought to light the interior decoration commanded by Francesco the Elder. The hall with the great cart (symbol of the Carraresi), the 'parrot' room, and another room with the initials of the signore all testify to the refined and cultured atmosphere of the Carraresi court. After the Venetian conquest the Torlonga was converted into a munitions store. On March 21, 1767 these stores were removed and further works began to adapt the tower as the new Astronomical Observatory. The present appearance of the upper part of the Specola (Viewing tower), with the observatories, results from the renovations conducted by Abbot Domenico Cerato and from further developments in the 1800s.