Research carried out in 2005 was the continuation of a systematic archaeological investigation that has continued for several campaigns since 2001. Research conducted from 2001 to 2004 confirmed the existence of remnants of the northern wing of the Palace of the Dukes of Ilok. The main parts of the northern wing were explored: the central hall with two columns, a smaller room in the middle and the western room, where traces of explosions were recorded during the 2003 survey. The new investigation was aimed at a clearer definition of individual details crucial for the understanding of the northern wing of the Palace of the Dukes of Ilok. It was established that the buttresses to the northern wall could not be completely defined at this level of the excavation. Large pieces had been broken off the buttresses and lay at a small distance from their edges. A wall discovered with a Baroque cellar in 2001 at the NE corner of the palace went on to the west with a slight deviation to the north, all the way to the westernmost buttress on the northern wall. Over the investigated area, modern sewage works were discovered that intersected this Baroque wall. Alongside the eastern buttress of the northern wing, a pit was discovered, in which the remains of two Rococo ceramic tiled stoves were found. The remains showed that they had been decorated with garlands and medallions in relief. Inside the central hall of the northern wing, the stratigraphy revealed by the research of 2002 and 2003 was confirmed. After the recent layers, a layer of rubble was found that was created when the fortification was broken down at the end of the 17th century. Below this was a layer of cinders and minor pieces of plaster, which was created after the palace was taken by the Ottomans and demolished in the 17th century. The layer was rich in finds of iron objects (locks, nails, projectiles). With the use of a metal detector, a number of lead and iron projectiles were found, as well as one partially preserved and two complete coins (one from the 16th century). As for moveable material, pieces of pottery from all periods were found, a balsamary, an oil lamp, a medieval spear, crossbow bolts, gilded parts of bones, Gothic and modern stove tiles, a coin (14th century), pipes, stone, iron and lead projectiles (Željko Tomičić, Marko Dizdar, Bartul Šiljeg, Hrvoje Kalafatić, Kristina Jelinčić 2006, Hrvatski arheološki godišnjak 2/2005, 26–28).

Archaeological excavations at the Palace of the Dukes of Ilok in Ilok have been systematically carried out since 2001. In the period from April 18 to October 13, 2006, the Institute of Archeology conducted the sixth season of archaeological and conservation works. The aim of the archaeological excavation was the restoration and revitalization of the archaeological and architectural complex of the Upper Town in Ilok, which is being conducted as a part of the "Exploration, restoration and revitalization of cultural heritage Ilok - Vukovar - Vucedol" project funded by the Government of the Republic of Croatia and the Council of Europe Development Bank. In 2006, exploration focused on defining the northern Gothic palace, the central courtyard, and the northwest corner with ramparts and towers. Numerous structures and features from the first quarter of the 18th century to the end of the 19th century have been recorded testifying to Baroque reconstructions carried out by members of the Odescalchi family over two centuries. Numerous pottery fragments and finds of coins testifying to life within the damaged Gothic palace can be correlated with the domination of the Ottomans, which lasted about a century and a half. Structures found in the central part of the northern half of the courtyard may belong to the remains of Ottoman architecture. The northern wing of the Palace of the Dukes of Ilok, built by Nikola Iločki in the middle of the 15th century, has been completely defined. It consisted of four rooms with plaster and brick floors. Under these later structures, late medieval, Roman-period and prehistoric layers were discovered, which testify to the continuous habitation of the Ilok Upper Town. Remains of Roman-period architecture and five early-imperial graves have been found. In the graves, numerous fragments of domestic and imported pottery, glass and bronze objects were found. Grave 5 with a sword in its scabbard and Roman military belt (cingulum militare) and tombstone 3 with a bronze scabbard stand out. Traces of continuous prehistoric habitation can be dated from the Late Stone Age to the Late Iron Age. The most intensively inhabited settlement, to which the largest number of excavated pits can be attributed, is recorded in the early phase of the Early Iron Age when the settlement of Kalakača phase of the Bosut group was located at the position (Željko Tomičić, Marko Dizdar 2007, Hrvatski arheološki godišnjak 3/2006, 38–41).