During the 15th and 16th centuries, along the Adriatic coast, we witness the construction of a series of anti-landing turrets: the "Torre sul Porto" is a typical example of these constructions (still present in Abruzzo, but almost completely disappeared in Marche). In fact, with the intensification of trade by sea, a different organization of the "port of Ascoli" became necessary, which needed to be defended from the incursions of pirates and brigands and from the spread of epidemics. The "Tower on the Port" was built in the first half of the 16th century: on 18 November 1543 the Lombard Mastro Battista Raffaele of Como communicated to the city of Ascoli the construction of the tower near the river port; the works on the octagonal tower ended in 1547. Towards the middle of the seventeenth century the plague was spreading like wildfire and so, in 1673, to protect the Ascoli area from the arrival of foreign goods, a new rectangular structure that partially incorporated the tower itself. This new structure was intended to house a permanent armed guard for the defense of the port and for health surveillance. The current structure of the building is characterized by a composite plan composed of a large central body with a rectangular plan called "casone", and a smaller structure with an octagonal plan inserted in part inside the first. Both structures have exposed brick masonry made up of regular courses interrupted only by a simple string course frame (cord), also made with bull-shaped bricks and with the use of short stone elements inserted only in the corners of the largest building. Over time, the ancient openings, loopholes and doors have been partly replaced by larger windows which are repeated with an irregular and asymmetrical rhythm both on the main facade and on the side elevations, allowing the infill panels of perhaps older openings to be glimpsed in the masonry. Inside the building there are the narrow rooms of the sixteenth-century tower where the criminals were relegated, then used as a home by the families of local sharecroppers (the building is also known locally as the "Olivo house", from the name of the last inhabitant ). The roofing system of both the sixteenth-century tower and the "casone" were replaced, in the nineteenth century, by a wooden structure on which the terracotta tiles and the roof tiles rest. The interior of the building is currently uninhabitable and requires major renovation works. On the sides of the main portal there were the rooms intended for the shelter of the livestock (south side), for the storage of cereals and for the agricultural and maritime shed (north side); these rooms, together with other annexes built in the second half of the 20th century, were removed in the conservative restoration works of the external parts in the years 2011-2012, except for the structure on the south side (former stable). Here the construction of a classroom with about 30 seats for environmental education activities and an info-point is planned, while the terrace above will become a privileged point of observation of the landscape and birdlife; unfortunately these works have been blocked for years, and therefore the Torre sul Porto is currently closed and unusable. To increase the importance of this property is its location within the "Sentina Regional Nature Reserve". Located north of the mouth of the Tronto river, it is a brackish marsh in which there are only very few rural buildings and which has a wetland of great biological and birdlife importance. Unfortunately, it is currently threatened by severe coastal erosion, with the sea now reaching the edge of the "Torre sul Porto".