Jepara Portuguese Fort was built by the Portuguese in 1632, when Sultan Agung ruled the Mataram Kingdom. This fort is the result of an agreement between Mataram and the Portuguese. The function of this fort was as a center of defense and to protect shipping lines from VOC threats because at that time Mataram was in conflict with the VOC. Jepara Portuguese Fort is administratively located in Banyumanis Village, Donorojo District, Jepara Regency. At first this fort was located in the Keling District area, but after the expansion of the area in 2008/2009, the existence of this Portuguese Fort is now included in the Donorojo District area. Geographically, Jepara Portuguese Fort is at the coordinates of UTM E 463236.41 and S 9277713.49 on the Indonesian Digital Earth Map Sheet Sheet 1409-622 with a scale of 1: 25,000 (Figure 1). The boundaries of the territory surrounding the Portuguese Fort Jepara are as follows: Highway to Jepara - Keling route and residential areas in the south, Java Sea to the west, Java Sea to the east, Java Sea and Mandalika Island to the north. The Portuguese fort was built on a hill jutting toward the sea (headland) which was flanked by two bays to the west and east. The cliffs of the hills on the west and north sides are steep cliffs with some rock solid outcrops. While the east side is a bit sloping and the entrance to the fort is through the cliffs of the south side of the hill which is not too steep in morphology. Geologically, the hill is a dense hill with a thin surface soil layer ranging from 20 to 30 cm which is the result of weathering of these solid rock. The Portuguese fort was built on the top of the hill on the north side. The fort is currently only a fence made of solid stone which is cemented (this cement still needs to be investigated, whether the mixture is current cement or former cement).
The fort has 3 doors consisting of one main door on the south side of the fort, one door on the west side and one door on the north side. On the north side of the fort there were 3 u-shaped holes which were possible to place the cannons facing the sea. In the center of the fort was a rectangular structure made of piles of rock fragments. On top of this structure a paving block footpath has now been constructed. Inside the northwest corner of the fort, an octagonal viewing post has been built. Behind the U-shaped hole in the fort walls a diorama of small cannons facing the sea is now built. Around the fort, paths of interconnected paving blocks have been built and all of them lead to the coast to the north and east of the hill as a way down or up for visitors either from the coast to the fort or vice versa. In the inner courtyard of the fort there were several children's games built but by the current manager these games have been removed and moved to the area near the entrance ticket booth. The new building is a viewing post built into the inner courtyard of the fort in the northwest corner. Under the hill on the west side and on the beach there is a building similar to the Portuguese Fort which is at the top of the hill. This building was built attached to a hillside similar to a cave. Goa here does not mean a deep horizontal or vertical cave but is formed from a fracture in the solid rock layer to form a cavity. Because it forms a cavity, some residents call it a cave. This building has three walls with cliffs as the fourth wall. It is not known whether the building has a permanent roof or not. The building faces west (west coast) with the main door on the west side and is located at the north end of the building wall. The height of the north side of the building wall at the west end is ± 160 cm and the east end attached to the hill has a height of ± 200 cm. The west side wall has a height of ± 200 cm, while the south side wall has the same height as the north side wall. On the north and south walls there are several holes with a diameter of ± 25 cm with an interval of ± 60 cm between the holes and the height from the ground is ± 160 cm. Source: Budaya.kemdikbud.go.id