Long before I arrived on the Greek island of Patmos it was clear that I was in for an inspiring experience. Although there were a few wealthy Athenians and foreign backpackers making the 10-hour ferry-trip from Athens, most passengers were ordinary Greeks, dressed in traditional garb.

A group of middle-aged women, their heads draped in dark scarves, frequently crossed themselves as they read their prayers and other religious texts. Another group sang hymns of praise; as they began to drift into sleep, a third group eagerly took over. These good people were not off to a holiday hot-spot; they were on pilgrimage to Greece’s most holy isle.

Approaching tiny, arid Patmos, one of the 12 islands of the Dodecanese, one could already see, atop a hill, the fortified Monastery of St. John, looking more like a castle than a religious retreat. Nevertheless, it is the most celebrated Greek Orthodox monastery outside the mainland and Patmos’s principal claim to fame.

The ferry cruised gently into the harbor. Pilgrims and tourists rushed to the bus connecting Skala, the port, with the upper town and the monastery, but I preferred to take my time. After dropping my bags at a guesthouse, I followed the traditional route to St. John’s: an old, cobbled mule track that wound gently up the hillside.

Twenty minutes later and about halfway to the monastery, I paused at the small Convent of the Apocalypse where, according to local tradition, St. John had his prophetic vision. Beyond narrow, white-washed, flower-bedecked courtyards, steps led down to St. Anne’s Chapel, founded in 1090 and built around a small grotto. A monk, quietly cleaning the iconostasis – a screen of icons dividing the nave from the sanctuary – pointed to a rock that is believed to have served as St. John’s desk. There were three fissures in the rock, said to be cracked by the voice of God.

St. John, traditionally regarded as the author of The Book of Revelation, was banished to Patmos in 95 A.D. by the Roman Emperor Domitian for preaching the Gospel in the Roman city of Ephesus. Parts of the biblical letters of St. John, a series of moral admonitions addressed to the seven Christian churches of Asia Minor, may well have been penned on that stone desk.

Leaving Patmos almost deserted, St. John returned to Ephesus following Domitian’s death in 97 A.D. When the Roman Empire embraced Christianity 250 years later, a small basilica was built in Patmos on the site of a pagan temple. The islanders, however, were forced to flee following Saracen raids during the early medieval period. For half a millennium the island was again all but deserted until, in 1088, Emperor Alexis I Comnenus ceded it, free of taxes, to Christodoulos, an abbot from Asia Minor now revered as a saint.

Throughout the Byzantine period, the monastery, while autonomous, maintained close contacts with the Byzantine capital, Constantinople, employing artists and craftsmen from that city. Patmos fulfilled its role as an important Shrine and pilgrimage center and produced several notable abbots such as Leontius II, who later became Patriarch of Jerusalem from 1176 until his death around 1190.

In the early 13th century Latin Crusaders, lured by the wealth and beauty of Byzantium, attacked, looted and occupied Byzantine cities, including Constantinople. Interestingly, however, they respected the autonomy of Patmos.

A provincial establishment, Patmos’s influence grew, ironically, as the prestige of the Christian powers of the East – Byzantine and Venetian – waned. In 1537, the monks negotiated a peaceful settlement with the Ottoman Turks, who promised to recognize the abbot’s authority if they surrendered the island peacefully. Indeed, along with Mount Athos, St. John’s was one of the few monastic centers able to secure a favorable agreement with the Turks. St. John’s, through education and the protection and care of important monastic artifacts, safeguarded Byzantine culture during the Turkish occupation of the eastern Mediterranean.

While the Ottoman Turks strengthened their hold on Asia Minor, monks, clergy and laity fled to Patmos. Few Turks chose to settle on the island and under monastic direction it became renowned as an intellectual center. Under the Turks, education was neglected throughout Greece, but on Patmos old traditions were maintained. As late as 1713 one monk, Makarios, founded the celebrated School of Patmos where Latin, rhetoric and philology were taught in addition to religious studies. Some of the school’s students went on to become theologians, patriarchs, politicians and revolutionaries. One such revolutionary, Emmanuel Xanthos, founded Philiki Etaireia (Friendly Company), a secret society established in 1814 that espoused Greek independence.

Even from their relatively privileged – if isolated – position, the monks of St. John were nevertheless deeply affected by the sense of despair in the Orthodox Church that followed the Ottoman Turkish conquest of the Byzantine Empire. Twice, in 1681 and 1725, the monastery announced communion with the Church of Rome, although this appears to have been more diplomatically than spiritually motivated.

Later Patmos became active in the cause of Greek independence, which was attained in 1827, but under the terms of the 1832 Treaty of Constantinople, the island remained under Ottoman Turkish rule. It was not until 1948, after being ruled briefly by Italy, that Patmos was finally reunited with Greece.

Clearly, St. John’s Monastery is of enormous historical importance. Today, only a handful of monks are in permanent residence, following their age-old tradition of service to pilgrims and other visitors.

Although many of those searching for a life of silence and prayer are attracted to more remote monasteries, such as those on Mount Athos, the monks at St. John’s form a living community. The monastery remains closely connected to the School of Patmos and is one of the most influential monastic houses in the Orthodox world.

What St. Christodoulos started, and his successors continued, is a magnificent achievement. From the mule track below, the monastery looms above pilgrim and passerby. As one enters the narrow, white-washed streets of Hora, the old town built around the base of the monastery, the building is temporarily lost from sight. Then up a cobbled ramp, past tight corners and the Chapel of the Holy Apostles, one arrives at the imposing medieval entrance.

Within lies a labyrinth of pebbled courtyards, great arches and whitewashed domes. Vaulted passageways lead from the old refectory to the catholicon, or main church, where St. John is portrayed dictating a passage of The Book of Revelation in a 17th-century fresco.

Like Mount Athos or Meteora, St. John’s Monastery developed in a rather haphazard manner. Some of the original 16th-century structures – many of the walls, the catholicon, the refectory and several cells in the southern wing – were built between 1088 and 1093, before the death of St. Christodoulos. In the following century a narthex was added to the catholicon, the refectory was remodeled and the Chapel of the Virgin was built to the north of the catholicon.

Surprisingly, the catholicon seems to have broken a golden rule of monastic design. Although based on the Greek cross-in-square plan, the church is almost entirely enveloped by annexes and out buildings and cannot be viewed as a whole. Even the dome cannot be seen from outside. Instead, the roof is a flat terrace commanding magnificent views of the harbor and the Aegean Sea far below.

To Byzantine monks, church architecture was less important than the symbolism of the church’s interior: the icons on the iconostasis, the elaborate silk embroideries, the paintings on the walls.

In the Monastery of St. John, two series of Byzantine paintings survive. The more complete of the two dates from the 12th century and was discovered under more recent paintings in 1958, during restoration of the small Chapel of the Virgin.

The restored chapel paintings had been executed in the academic style of their time. Static figures were portrayed symmetrically and, usually, fully frontal. Elements such as saints’ beards or hair were reduced to separate volumes and there was little or no background setting.

In the sanctuary vault, paintings based on Christ’s miracles share the common theme of water, which cures, quenches thirst and symbolizes the word of God.

Elsewhere in the chapel figures of saints, including seven church fathers and a series of patriarchs of Jerusalem, are depicted as busts or full-length figures. These portraits, as well as providing valuable historical information, help date the paintings.

The most recent figure is of Leontius II, Patriarch of Jerusalem from 1176 until his death around 1190. As noted above, Leontius was abbot of St. John’s before his patriarchal election and he probably held both posts simultaneously until 1180. It is thus supposed that Leontius donated the money and supervised creation of the murals during his last four years as abbot.

Paintings in the catholicon, dating from around 1600, are markedly different in style and feeling. They are difficult to make out in the dark but with the aid of a lighted candle one can identify scenes from the Nativity, the Slaughter of the Innocents and the Parable of the Ten Virgins.

St. John’s also houses remarkable religious artifacts. Some of the monastery’s oldest books and manuscripts date back to its foundation. Among them is the monastery’s most precious document, the chrysobul of Emperor Alexis I Comnenus ceding Patmos to St. Christodoulos.

One of the earliest illuminated manuscripts in the library is a copy of The Book of Job that predates the founding of the monastery and is written entirely in uncial letters, which were the norm in fourth- to eighth-century manuscripts. There are also 33 leaves of St. Mark’s Gospel, Plus the Codex Purpureus from the sixth century, written in silver lettering on purple vellum.

Also on display are gifts from benefactors such as Catherine II of Russia, who donated a silver cross and medallions, as well as gifts from priests and patriarchs who were born or studied on Patmos. Anonymous donors have given votive offerings of small silver boats and liturgical vestments embroidered with gold and silver thread.

St. Christodoulos may well have founded St. John’s, but its wealth and influence have depended as much on the generations of pious supporters and the multitudes of pilgrims who still make the long journey to the holy island each year.

Chris Hellier is the author of Monasteries of Greece, published by Tauris Parke Books and distributed by St. Martin’s Press.