As a result of being affected by the colonial ruling, several fortresses were built by sovereign countries. The Jaffna Fort which was built by the Portuguese in 1618 is the largest fort used for military purposes. This fort in star shape is situated in the coastal township called Gurunagar. After capturing the Jaffna city, the Portuguese started the construction work of this fort in 1618 under the guidance of Portuguese general Phillippede Oliveira.
Later in 1795, it was renovated by Dutch without making any major changes. The significance of this fort is that it is a blend of both Portuguese and Dutch architecture. Unlike the forts in Galle, Matara
Batticaloa and Trincomalee, the Jaffna fort has totally been built with granite stones. There are several bastions placed at five points that would bring the utmost protection to the inmates of the fort. The Interior of the fort has completely been designed in a way to help the military purposes. There is a significant difference when compared with the other fortresses in Sri Lanka. That is the protective canal that has been built around the fort except along the sea border.
During wartime, this fort was under so many calamities. It was under L.T.T.E. and Sri Lanka government from time to time. A long ten-year period from 1985 to 1995, was under Tamil cadres and it was recaptured by the Sri Lanka army in 1996. This was heavily damaged and later in 2010, renovation work was completed.