Pylos Fort (Niokastro) started being built by the Othoman in 1573, shortly after their defeat at the Battle of Lepanto (1571). The goal of its construction was the control of the south entrance into the bay of Navarino, since the north access (Strait of Sykia or Faltsa Mpouka) and the harbor there, at the lagoon of the Divari or Rivari area, couldn’t be used because of alluvial deposits. It was named 'Niokastro' as opposed to the anterior fort of Koryphasion (Paleokastro or Old Navarino), which used to control the north entrance and the old harbor.

Since then Niokastro followed the common fate of the other forts of the area, being involved in the historical events that marked the area. It remained at the posession of Turks till 1686, when it was surrendered to the Venetians. In 1715 the Turks reoccupied Niokastro, Koroni and Old Navarino. In 1816 Ibrahim Pasha became ruler of the castle till 1828, when it was freed by the French general Maison. After the liberation of Greece (in the World War II) the fort was used for some time as prison before it was finally given to the Archaeological Service. Therefore, many damages, repairs, alterations and additions can be noticed.

Its today's form consists of the hexagonal citadel and its outwork, two quadrilateral, enclosed bastions (the west, called 'Seventh', that controls the entrance into the bay, and the north, of the "Tzafer Pasha" or "Santa Maura" that overlooks the harbor), the city walls joining those parts and the four cylindrical towers that strengthen it. From the "within the walls" settlement, few buildings survived. The information, however, of the Evliya Celebi that it was built in a place where previously there was nothing, has already been questioned due to the opposite indications generated in the course of the required work for its formation as "Centre for Underwater Archaeological Research'.

The idea for the establishment of the 'Center' is attributed to the then Director of the Ephorate of Underwater Antiquities Georghios Papathanasopoulos. Thanks to his concerted efforts, in spring 1982 the projects with funds of the Ministry of Finance through the Archaeological Society were launched. Since 1991 expenditure is covered by funds managed by a special body of the Ministry of Culture.
The projects of restoration and new use of the premises have mainly focused on the citadel, where the former prison cells were fashioned in offices, warehouses, workspace and some of them, in the form of open canopy, cover semi out-door exhibition needs. Furthermore, the gunpowder became conference or exhibition room. Already in 1984 Niokastro hosted the 3rd International Conference in Underwater Archaeology and since then has covered the needs of several cultural events in the area.

In the recent past the restoration of the eastern cylindrical bastion, which bears according to folk tradition the name of General Makriyannis, was completed, with the aim to form it into a permanent indoor exhibit space.

In the context of the building programme of the "Center" also the building of the barracks of the french expenditionary force of the period 1827-1830 was restored from the semidilapidated state that had fallen. It is defined as "Barracks of Maison", named by the in charge French general. The floor of the 'Barracks' was turned into library for the needs of the 'Center', where the donation of the 'Messenian' library of the publisher Notis Karavias is hosted as well. It includes additional accomodation space for short stay for researchers and scientific or other personnel.

The ground floor was destined for the exhibition of the collection of the French philhellene Rene Ρuaux, which according to his wish, should be housed in Pylos. Its greater part was hosted between 1961-1984 in 'Antonopouleion' Archaeological Museum and afterwards was taken for conservation and exhibition. The rest that was stored since 1936 in the greek kiosk in the campus of Paris, was transferred in 1986 in the National Gallery under the care of Mr. G. Papathanasopoulos and delivered in 1992 in the Ephorate of Underwater Antiquities so that it reached its final destination. In 2012 the exhibition was transferred in the 1st floor of the building of Tsiklitira in the Harbor of Pylos.
The restoration work till 1998 was fulfilled by the personnel of the Ephorate of Underwater Antiquities.

Funding: Ministry of Culture and Sports, Archaeological Society