During the late autumn (November – December) 2005, an archaeological survey and test excavation of a site from a hitherto unknown period was carried out. It is a visible elevation – an oval mound of about 25×15 m, which is about 1 m higher than the surrounding area, and is located at the bottom of the valley through which runs the stream Donjica (local name is Donje Gradišće). The site is located along the old pedestrian path that led from Pokupsko to Kravarsko and further to Velika Gorica, and is about 500 m as the crow flies in a northeasterly direction from the chapel of St. Trinity in Gladovac Pokupski. Previously, a digital relief model was made at that location as well as geoelectric mapping. The area of high values of electrical resistance was spatially limited to that elevation and differed significantly from the values of the surrounding area, which indicated a very likely anthropogenic character of the measured values, and thus the existence of archaeologically interesting structures.
Since the site was overgrown with shrubs, it was necessary to clear and clean the area for test trenching. The site is surrounded by very moist and swampy land, firmer clay is only found on the north side of the forest road. In the immediate vicinity (on the south side) flows the stream Donjica, which has a smaller tributary further north. Based on the results of geophysical surveying, positions were determined for four smaller test trenches S 1 – 4 (two trenches with dimensions 3×2.5 m, one 3×2 m and the last one 2×2 m) with a total area of 25 m². Beneath the relatively thin layer of forest humus was a layer of burnt wood with crushed and burnt fragments of bricks, lumps of fine wood, remnants of burnt wood, and pottery fragments. Several iron nails and wedges were also found, a glass bottle neck, a small metal ball (part of a mace?) and a round bronze fitting with traces of wood on the back. Numerous pits and holes for wooden posts and smaller semicircular wooden supports, as well as a ditch 80-90 cm wide were discovered under this layer. Burnt remains of horizontally laid beams were found along the edges of this shallowly dug ditch. The filling of all these pits and holes was identical to the upper layer, and the pits were dug into impermeable yellow clay. According to preliminary research, the ceramic fragments would belong to the 15th and 16th centuries.
Considering the finds, it can be assumed that these are the remains of a destroyed settlement – perhaps a smaller fort or refuge, whose buildings were built of wood and earth and probably abandoned after being destroyed in a fire. Since no animal bones were found, as well as other waste material, it is possible to assume that the excavated area was used for non-residential purposes (workshop, storage or similar). The elevation area of 350–400 m² is too small to accommodate a settlement, but it is possible that it is only part of a larger whole (which will eventually be shown only by future research). Namely, the position called Gradišće extends over a much larger area in the direction of the east all the way to the foot of Gornje Gradišće hill. Not far from that location, at the position of Levišće, there was allegedly a church (according to the locals of Gladovac). Unfortunately, this area is now planted with a pine forest and it is not possible to get a solid insight.
Taking into account all of the above, it can be concluded that this is a single-layered late medieval site from the turbulent times of Turkish invasions. The abandonment of that location could be due to Turkish incursions during the second half of the 16th century. Test trenches gave positive results and the plan is to increase the scope of archaeological research. An attempt will also be made to locate more precisely the position of a possible church at the position of Levišće (T. Pintarić 2006, Hrvatski arheološki godišnjak 2/2005, 149–150).