The ruins of the ancient Acropole of Kastelorizo are situated 2 km southwest of the island's capital. Excavations in the area brought to light Neo-Lithic tombs, ancient and Byzantine constructions, cisterns, towers and Hellenistic Cyclopean walls. Tools and other objects found in the area are now exhibited in the Archaiological Museum of Kastelorizo.
The Archaeological Museum of Kastelorizo has been housed in Konaki since 1841. Konaki is an exterior rampart of the Castle especially designed for this purpose. Among the exhibits are findings from the excavations of Nikolaos Kyparissis in 1913; findings from the excavations of Michail Komninos, as well as objects from his private collection; Roman statues and Hellenistic inscriptions and icons from St Nicholas's church. It also includes parts of the old church, which stood on the site of St Constantine and St Helen's church. In another room, there is a small folk art collection of traditional attires, musical instruments, embroidery and jewelry.
The church of Agios Constantinos and Agia Eleni is the Metropolis of Kastelorizo. It was built in 1835, in Gothic style, upon the ruins of an older basilica. Tradition claims that the latter was built by Agia Eleni, to thank the Lord for protecting her from a storm while on her way to find the True Cross, in the Holly Land. The twelve granite columns supporting the church's roof were moved here from the temple of Apollo in Lykia, which was later transformed into the orthodox church of Agios Nikolaos.
The church of Agios Nikolaos is perched on the hill of the Castle of the Knights, also known as the Castle of St John. According to tradition, St Nicholas was born in Patara of Lycia, opposite Kastelorizo, and he preached christianity to the surrounding areas. His remains were stolen and taken to Bari by Italian sailors. The Dominican monks of the monastery of Agios Nikolaos organize festivals there each year to honour the saint. In the past, especially after the fall of Constantinople, which caused many Metropolitan Bishops to flea to Kastelorizo, the church had known better days. This is proven by its treasures, which are exhibited in the Monastery of Agios Ioannis Theologïs in Patmos. However, there are still some notable frescoes in its interior, and on its feast day on the 6th of December there is a large festival.
The Castle of Kastelorizo was built in the 14th century by the Magistrate Juan de Erendia on the site of an ancient temple built by Sosicles. It is perched on a reddish rock (Castello-Rosso), which gave its name to the island which until then was called Megisti. It was built in order to protect the island from pirates. In 1788, Lambros Katsonis forced the Turks to abandon the island. Since then, it has also been called Castle of Lambros Katsonis, or Castle of St John from the adjacent church of the same name. It used to have double fortification walls, embrasures, and several towers. Today, only parts of the fortification walls and the three towers bear witness to its glorious long history. In the surrounding area, there are redecorated windmills and remains of Turkish baths.