Ialysos is one of the three ancient cities of Rodos with remains of occupation dating back to 3rd millennium BC and also settlements & cemeteries dating from the Mycenaean-Minoan period.
The building remains of ancient Ialysos discovered to date are mainly on the Filerimos hill, which was given this name in Byzantine times. Its earliest known name was Achaia, which is further evidence for the presence of Greeks in this area during the Mycenaean period, Strabo calls the hill Ochyroma ('Fortification').
From very early times the hill was in fact used as a strong point and also as a place of worship. Late Classical and early Hellenistic remains preserved on the acropolis of Ialysos include a Doric fountain-house and the foundations of the temple of Zeus and Athena Polias. The Doric fountain is on the steep south side of the hill, on a small plateau in the almost vertical rock-face. It takes the form of a stoa constructed of poros and comprises a closed cistern, a second, open cistern with six pillars, linked by closure slabs, and a facade in the form of a stoa with six Doric columns. Waterspouts in the form of lion's heads, set in the closure slabs, channelled the water onto the floor of the stoa.
The third pillar has a late Hellenistic inscription carved on it, listing the penalties to be inflicted on anyone profaning the sanctity of the fountain. The remains of the temple of Zeus and Athena Polias are at the highest point of the Filerimos hill. It is an amphiprostyle tetra style Doric temple of poros. The foundations for the cult statue are preserved at the north end of the cella.
Architectural members from the ancient temple were used n the construction of the three-aisled Early Christian basilica constructed on the same site in the 5th or 6th c AD, of which the baptistery is still preserved, in the area of the south aisle. The baptistery is in the shape of a cross, the arms of which have curved ends, and the interior is riveted with marble slabs.
The north aisle of the basilica, which is precisely above the ancient temple, was repaired in the Byzantine period and converted into an aisle less church. The tiny aisle less church of Ai-Yorgis Chostos , to the west of the ancient temple, apparently also belongs to the Byzantine period. In the 15th c. its walls were covered with paintings depicting the Passion and the Life of the Virgin Mary, as well as a series of Knights with their patron saints.
Although they were basically western in style, these wall-paintings were influenced by the Byzantine painting tradition. To the west of the square created to accommodate visitors to the site, the catholicons of a monastery complex dating from the 10th c. AD has been excavated, it is a three-aisled cross-in-square church with three apses and a dome supported on four columns. The Byzantine remains include the ruins of the Byzantine fortification of Filerimos.
At the eastern end of the flat summit of the hill an entire garrison complex has been restored, which was repaired and used during the period of the Knights of St. John. The church built by the Knights, in the 14th c., originally consisted of two hexagonal chapels in the area of the aisle less Byzantine church. It was modified in the late 15th c., though retaining its distinctive double form, since the icon of the Panayia Filerimou was worshipped by both Orthodox and Catholic Christians.
During the period of Italian rule (1912-1945) a 'Golgotha' was built: this was a series of shrines with relief scenes of the Passion, which leads from the square to the west edge of the plateau of the Filerimos hill. Also a 30m stone cross was constructed but it was destroyed during the WWII. In 1996 a 16 metre cross was rebuilted on the top the plateau from which you can enjoy the view.