The earliest archaeological remains at the site date to the Hittite era of the 2nd millennium BCE, when the site was known as Apasa. There is also evidence of some Mycenaean presence before the start of the Helladic period around 1050 BCE. The hill is known to be the original location of Ephesus, before it moved to a new location a few kilometers away.

As with the outer fortifications the citadel walls were built with rubble stone and are strengthened with fifteen towers. The citadel of Selçuk has two major gates, one on the eastern side and the other on the western flank.

The castle was built during the Byzantine era (circa 6th century CE), however the current fortifications vear traces of Aydinid and Ottoman Imperial era reconstructions as well. Thecity walls of the inner castle made ofrubble stones.

circa

Ayasuluk Hill represents the earliest and longest-occupied nucleus of settlement in the Ephesian region, with archaeological evidence attesting to continuous or recurrent habitation from the Chalcolithic and Early Bronze Age onward. The hill’s commanding position above the Küçük Menderes (ancient Cayster) plain made it a natural stronghold, and during the second millennium BCE it likely functioned as a fortified acropolis associated with the Arzawan and later Mycenaean cultural spheres. Hittite texts referring to Apasa, generally identified with Bronze Age Ephesus, are thought to correspond to a settlement centered on or near Ayasuluk Hill.

In the Iron Age and Archaic period, political and cultic activity gradually shifted downslope toward the Artemision and the developing Ionian city, but Ayasuluk Hill retained strategic significance as a defensive refuge. During the Classical period and Hellenistic period, when Ephesus expanded as a major urban and commercial center, the hill was no longer the primary seat of administration, yet it continued to be occupied, likely hosting small fortifications and watch installations overseeing the fertile plain and maritime approaches.

Under Roman rule, Ephesus reached its greatest extent as a port city, and Ayasuluk Hill remained marginal to the monumental urban core. Its importance rose again in Late Antiquity as environmental and economic changes undermined the lowland city. Progressive silting of the harbor, recurrent flooding of the Cayster plain, and a series of destructive earthquakes in the third and fourth centuries CE encouraged population movement toward higher ground. By this period, the hill began to serve as a focal point for resettlement and defense.

The transformation of Ayasuluk Hill into a major religious and urban center occurred in the sixth century CE with the construction of the Basilica of St. John under Emperor Justinian I. Erected over the traditionally accepted tomb of John the Evangelist, the basilica elevated the hill to international prominence as a pilgrimage destination. Substantial fortification walls, towers, cisterns, and ancillary buildings were constructed, effectively redefining Ayasuluk Hill as the fortified heart of Byzantine Ephesus. This shift marked the final abandonment of the Roman city below as the principal urban center.

From the seventh to the tenth centuries CE, Ayasuluk Hill functioned as a fortified stronghold during periods of Arab-Byzantine conflict. Its walls were maintained and reinforced, and the settlement endured as a reduced but resilient urban enclave centered on the basilica. Even as Ephesus declined from a metropolitan city to a provincial stronghold, the hill preserved its religious prestige and strategic role.

Following the Seljuk capture of the region in the late eleventh century, Ayasuluk Hill entered a phase of cultural transition. Byzantine occupation gradually diminished, though the fortifications remained in use. In the fourteenth century, under the Aydinid dynasty, the construction of the İsa Bey Mosque at the foot of the hill symbolized the emergence of a new Islamic urban center while incorporating spolia from the Byzantine basilica above. With the Ottoman consolidation of western Anatolia in the fifteenth century, Ayasuluk Hill lost its administrative importance but remained a prominent landmark, its stratified remains reflecting over four millennia of settlement, religious transformation, and strategic continuity.

circa 550 CE

Selçuk Citadel
The citadel is located on the highest point of the Ayasuluk Hill, to the north of the Church of Saint John. The rocky platform on which the structure of the citadel is situated forms the upper most part of the Ayasuluk Hill. The fortress of Selçuk bears a long and very active history. The walls seen today belong to the Seljuk and Ottoman periods. The citadel enclosed several important structures including a royal palace, water-cisterns, a small mosque and residential houses for notable people.

circa 550 CE

Gate of Persecution
The main gate called "Gate of Persecution", located to the south of the building complex has remained as the most intact portal among all the entrances to the acropolis complex. Thegate has square-plan towers on both sides and an arched entrance portal at the center. The upper section of the arch contains a sarcophagus-like surface relief of Eros. Beside this, there were other relisfs (found until 1800s) about the prosecution scene of Hector and Achilles. Reliefs were removed to England in 1812 CE and put on display in the Woburn Abbey Gallery.

Some of the faded relief-frescoes still remain at the upper part of the arch. There are three medallions in the curly branch along upper part of the arch. There are possible depictions of prophets and saints in three aureoles fields. On the side of the frames there are two rectangular fields as well, depicting figures seeking east and west. Jesus is also depicted in the middle with his seven apostles. These frescoes have been dated to the 8th century CE or later.

circa 1374 CE

Mosque of Isa Bey
The Isa Bey Mosque (İsa Bey Camii) is one of the most delicate examples of Seljukian architecture, situated below the basilica of Saint John. The mosque was built by the master Syrian architecture Ali son of Mushimish al -Damishki, between the years of 1374 and 1375. The mosque was styled asymmetrically unlike the traditional style, The location of the windows, doors and domes were not matched, purposely. In the entrance of the mosque, an inscription from the god decorates the doorway. The columns inside the house of prayer are from earlier ruins in Ephesus, making an interesting contrast to the mosque. The domes are ornamented by turquoise and blue faience, revealing the characteristic of Ottoman style. Crown-like doors from Seljukian architectural style later combine with the specific decoration elements of architectural style.