By the 3rd century AD, Christianity arrived in the city. The city was a diocese under the Metropolis of
Myra in Lycia.
Methodius, known as Methodius of Olympus, was the first bishop of Lycia and Olympus in the late 3rd century AD. The texts he wrote in response to anti-Christian writings are important in terms of the first efforts to recognize Christianity. Methodius was probably
martyred in 312 AD. The names of the bishops known after Methodios are important for the history of Olympus. Other known bishops are Aristocritus who attended the
Ephesus Council in 431 AD, Anatolius who was mentioned in the letter sent by the Myra metropolitan administration to
Leo I dated 458 AD, and Ioannes who participated in the Constantinople Synods of
518 and 520 AD. Also, another bishop of Olympus named Anania/Anianus or Ioannes was also identified on a lead seal dated to the beginning of the late 6th-7th century AD. The names of bishops Theophiletus and Nicholas can be read on a chancel screen and a door lintel which were uncovered during archaeological excavations in the Episcopal Church. The name Olympus also appears in the
bishopric lists of the 5th-7th centuries AD. The name of the city was last mentioned in the 9th century AD when it was affiliated with the Metropolitan of Myra. It is possible to say that the urban texture of Byzantine Olympus, formed by an intense development program that took place in the 5th and 6th centuries, was based largely on the Roman period city. Although the streets, roads and the settlement plan in the city had changed, they still seem to correspond to the layout of the Roman city in general. While some widening and/or narrowing can be observed in the streets as compared to the Roman period, general directions and layouts of the streets remained the same. The most important change with the Byzantine period is the expansion of living spaces in the city. Considering the location of the buildings, it is possible to say that the early Byzantine city was larger and had inhabited a larger population than the Roman period. The civic texture of the southern city had expanded towards the slopes of the Sepet Ridge toward the south-east direction. In the northern city, civil buildings were built on Necropolis Street and Roman period tombs were utilized as living spaces. There are nine churches in the city center belonging to the early Byzantine period. Olympus is known to have an extensive territorium, yet it is remarkable that as a medium-sized settlement its city center has nine churches. All churches are three-aisled basilicas and two of them have a transept. All of the churches have opus tesselatum mosaics on their floors and were richly decorated. The southern hillside settlement is situated in a terraced area supported by retaining walls. There are east–west oriented passages between the terraces and stairways that allow access between these passages. Beam holes and buttresses show that problems due to differences in elevation in the naos of the churches located on these terraces were solved by wooden flooring. Four of the churches in Olympus have atriums. The atrium of Church No. 8 is on the north side, while the atriums of Church 1, 3 and 6 are located to the west side. Churches with an atrium do not have narthexes, while others have narthexes to their west. The main reason for the absence of an atrium and narthex together is the scarcity of land in the city. The churches constructed on the layout of the Roman period have individual plans according to the parceling of the insulae in the city and some distortions were observed in the plans of the churches due to the remains of the previous buildings. No longer a residential bishopric, Olympus is today listed by the
Catholic Church as a
titular see. == Modern times ==