Antiquity was succeeded by the Byzantine era. The worshiped gods changed form, but the natural space of Parnitha always inspired man to contemplate the uncle in the magical atmosphere of the vast forest. The German L. Ross, the first professor of archeology at the University of Athens, expressed the view, which was later accepted, that the spread of Christianity in Attica began in the countryside.
- In 1209 Pope Innocent III in his famous parliament noted villages and monasteries that would be taxed from now on by the Catholic bishop of Athens. “Kyriomonastiro” is also mentioned among them. The order of recording leaves no doubt that it is the monastery of Hassia, the Monastery of Kleiston and if the explanation of the linguists does not accept that the Kyriomanastiro means “the monastery of Kyra”, but “Choriomonastiri”, then it can be concluded that around the old Monastery there was a Christian village, chased by ruthless pirates. The antiquity of the monastery is a given. The Monastery is dedicated to the Assumption of the Virgin Mary and is called “Panagia ton Kleiston”. It is a nunnery with twelve (12) nuns under the abbess Mariam. The Katholikon belongs to the type of two-inscribed cruciforms with a dome and to the north it has a continuous chapel with a square sanctuary arch. The katholikon bears traces of frescoes, while the consequences of its burning by the Turks in 1821 are obvious. It is located on the south-southwest side, 4km from the village of Fili. Initially it was a male Monastery and when it was founded all the ascetics who practiced in the caves of the area gathered there.
- In the heart of Parnitha and below Karavola, its highest peak, in a sheltered place at an altitude of 1000 m. With the source “agiasma” and the thousand-year-old walnut tree that dried in 1955, the Catholicos of the old Monastery of the Holy Trinity is still preserved , Metochi, of the Petraki Monastery since 1796 with a sultan’s firman and a patriarchal sigil, designated a “crossroads” to prevent its disappearance. It is the only asset left up there in the Petraki Monastery. Already with Law 3028/2002 article 7 the church, like all the Byzantine monuments, belongs by prefecture and ownership to the State, while since 1998 it has been considered a protected monument. The church was damaged during the 1999 earthquake. The frescoes from which the church is recorded date back to the 17th century. Unfortunately, the damage from the earthquake has not yet been restored in the Katholikon of the old Monastery, which belongs to the type of single-aisled cross-roofed churches with a narthex.
- At a distance of 2 km from the Tribe at an altitude of 470 m. There is the male monastery (Old Calendarists) of Agios Kyprianos and Justin that was founded in 1961.
- On the south side of Parnitha, northwest of Acharnes, at an altitude of 510 m. Is the nunnery of Genesis of the Virgin Dardiza founded in 1969.
- In the southern accesses of Parnitha was the Metochi of the Holy Trinity with two (2) churches, the Prophet Elias and the catholic “Agios Nikolaos, the young”, with its important frescoes of the 17th century. Unfortunately, the earthquake destroyed the church of Agios Nikolaos and seriously injured the church of Profitis Ilias, which was “repaired” arbitrarily. Both churches are single-aisled, vaulted, basilicas with a semi-hexagonal sanctuary arch.
- Of the preserved churches, the one of Agios Mercourios is noted in the passage – Derveni to the “European land”. The French consul in Athens in 1774, J. Girand, mentions the church and connects its name with the arrival of the Arvanites there, from 1383 AD.
- On the northeast side of Thrakomakedones, the church of Agios Nikolaos, a small cruciform church with an octagonal dome roughly dated from Orlando in the 16th century, is located on the site of a newer monastery of ancient calendarists. After the earthquake the church was damaged and from the research that followed, it was announced that a mural decoration of the 13th century was revealed, classifying the monument as Byzantine.
- West of Thrakomakedones the church of Agios Georgios of “Vourdoubas” in the area of the Municipality of Acharnes, vaulted, basilica with a semicircular arch of a sanctuary at the beginning of the gorge of Houni. The dimensions of 4.50×6.20 m. Are noted for historical reasons, because the earthquake of 1999 has made it completely dilapidated. To date, no care has been shown for its fate, while the fire of 2004 deprived its surrounding area of greenery.
- In the stream of Agios Georgios at an altitude of 840 m. Is located in recent years renovated by the Municipality of Ano Liossia in the vital area to which it belongs, the desert church of Agios Georgios of Keramidi. It is a small, single-aisled, royal church with a semicircular arch of a sanctuary and without frescoes, to the east of which an old threshing floor is preserved. A little south of the church passes the forest road Metochi – Rema Agiou Georgiou – Avchenas Bontias – Paleochori – Agia Triada 10 km long. In 1995 the Municipality of Ano Liossia renovated the church. During the arrangement works, a Christian tomb was discovered southwest of the church. After radio dating of the bones, which took place in “Demokritos”, it was found that they date between 900 and 1017 AD. with a probability of 95.4%.
- Further south in the foothills of Parnitha is the old church of Zoodochou Pigi in Gatzana.
- Deep in the forest of Parnitha at Mola, where the Parnitha ring road passes, it is renovated by the Ministry. Georgia, the desert church of Agios Petros (single-aisled, vaulted, basilica, 3,80×8,10 m.), With a semicircular arch of a sanctuary and a rectangular building on the south side that the renovation maintained (altitude 1060 m.). During the works, Byzantine tiles were found, traces of kurasani in the old coating and a Christian tomb on its north side.
- In Loimiko there is a small church of Agios Georgios with a southern building – a room for the lumberjacks, who spent the night here (altitude 770 m.). The 1999 earthquake pushed a huge rock that cracked the north wall of the church. The name “Loimiko” connects the wider area with a possible place of refuge of the inhabitants of the surrounding villages in cases of plague.
- Even further north, the church of Agios Nikolaos in the “wells” is preserved in the same forest property of Loimikos. It remains an upright landmark of the Menidian land. Located at an altitude of 530 m.
- In the source of Fili is noted the church of Agia Paraskevi which was the base of Thrasyvoulos in antiquity, since northeast of the source there was the famous fortress.
The tour mentions the churches of Parnitha that are of some interest as well as the monasteries that have a monumental character.
Starting from the churches that have disappeared today, the church of Agios Athanasios is mentioned in the Tatoi forest forest, which was destroyed in a fire in the 1970s. Archaeologist Theofania Arvanitopoulou mentions interesting old frescoes.
In Varybobi, next to the big spring “Kontita” there was the church of Agios Ioannis, with the erected columns that are thrown in the area, where today there is a makeshift iconostasis.
At the location “Petra midnight” – Pigi Katsigianni and near the stream of Goura there was the church of Agia Paraskevi. Archaeological findings in the surrounding area show the antiquity of the church in combination with the ruins of a Byzantine settlement called “Paleochori”, a place inaccessible through the centuries and refuge from the rays, either from the fear of pirates or plague epidemics that plagued Attica for centuries. . The church is preserved today, roughly with concrete blocks, by pious Hasiotes.
The desert churches and monasteries of Parnitha and the plain are not only landmarks in the history of the place, but also places sacred and sanctified for centuries, places of prayer and communication with God.
Remarkable in the mountainous area of Parnitha is the presence of the Sarakatsani nomads, who for centuries moved their flocks in the spring in the cool meadows of the mountain and in winter they descended to the surrounding winters. The Sarakatsani lived there in permanent or occasional settlements and the monks of the monasteries continued to cultivate the monastery cross-fields, as archival studies have shown. They sowed a variety of wheat in the month of March and in two months they threshed. Traces of the old threshing floors are preserved even today.
Remarkable data from historical texts and archival studies have shown that since the Byzantine era the monasteries of Parnitha (Monastery of the Closed, Agios Ioannis Theologos, Agia Triada and Metochi) did not cease to function in the difficult centuries of Ottoman rule, and the monastery amount to several thousand acres.
After the liberation, robbery prevailed in the area throughout the 19th century, with the result that the mountain and the monasteries were deserted, with the exception of the Monastery of Kleiston. Only the lumberjacks and the Sarakatsani nomads with their flocks continued their activity on the mountain. The latter even had close relatives with the robbers, as is known and archival research has revealed.