Late on a peaceful night in May, on a quiet island in the Sea of Marmara, I walked alone on a curving street edged by walls dripping with ivy. Behind the walls, palms and red pines loomed above Ottoman mansions that drowsed in the leafy darkness. With no sound but my own footsteps, I continued down a slope that led to my seafront hotel. Then I paused. Ahead of me, in the half-light cast by a streetlamp, I saw a cluster of tall, undulant shapes at the turning. "Women, or horses?" I wondered. Nearing, I nodded: horses.

And then I laughed out loud. How on earth, in the 21st century, was it possible for me, or for anyone, to succumb to such poetic confusion? It was possible only on an island like the one where I found myself: the island of Buyukada, an hour's ferry ride from Istanbul, a place where time stands still.

For more than a millennium, Buyukada has lured travelers from the Golden Horn to its lush hillsides, dramatic cliffs and romantic coves.

Only 2 square miles in size, Buyukada, population 7,000, is the largest island in a green, hilly archipelago that rises from the Sea of Marmara like a convoy of basking turtles. The islands -- known as the Princes or, in Turkish, Adalar -- are actually a far-flung district of Istanbul, but unlike the city on the mainland, with its roaring traffic, cafes and skyscrapers, they don't seem to have gotten the text message that the 21st century has arrived. It isn't entirely clear that the message about the 20th has arrived, either.

To set foot on Buyukada is to enter a living diorama of the past, wholly preserved. There are no Starbucks here, no skyscrapers, no cars; only bicycles, horse-drawn buggies (called faytons), filigreed mansions and tile-roofed villas set amid flowery lanes and emerald hillsides that drop down to rugged beaches.

Having been to Istanbul twice before, I wondered why I had never heard of this offshore Shangri-la. Intrigued, I hunted down whatever information I could find and learned that the Byzantine Emperor Justin II had built a palace and monastery on Buyukada in A.D. 569. More monasteries followed and in ensuing centuries they became prisons for emperors, empresses and patriarchs who fell out of favor on the mainland.

But during the Ottoman era, Buyukada transformed itself into a pleasure island. Greek fishermen made their homes there; and, eventually, wealthy families built elaborate mansions (kosks) and comfortable villas (konaks).

For the first half of the 20th century, the island was popular among prosperous Greeks, Jews, Armenians and Turks, for whom it served as a kind of Hamptons. But when Greeks left Istanbul in the 1950s, following a wave of violence against minorities, they left their wooden summer homes behind. In their absence, the island fell out of vogue.

The island that had been named for an emperor became a day trip destination for poor residents of Istanbul seeking affordable leisure -- picnics on the piney beaches of the Dil Peninsula and horse-drawn fayton rides.

But over the last decade or so, interest in Buyukada has revived. A number of old Istanbul families are returning to their summer houses, well-heeled investors are renovating old properties, and a handful of academics, artists, writers and foreigners have come here to retreat from modernity, setting up stakes in Arcadia. The place is a time capsule, an hour by sea and a hundred years in time from the bustling Bosporus.

Brush with ghost of royalty

My host, Owen Matthews, agreed to show me the island's attractions, along with his sons, Ted and Nikita, ages 5 and 8.

On Owen's recommendation, I stayed two blocks from the clock tower, at an Art Nouveau-flavored wedding cake of a hotel called the Splendid Palas. Built in 1908, the hotel is double-domed, white as icing and grandly down-at-heel, with four tiers of balconied rooms and creaky crimson shutters. Wallis Simpson and Edward VIII once stayed there, and when I ascended the marble staircase, I almost expected to see the Duke and Duchess appear in the hotel's fountained atrium, dancing a ghostly tango.

We set off to have lunch a couple of blocks away, but the walk reminded me of the 19th-century panoramas you might stroll past in a museum exhibition. Wisteria tickled our heads as we edged alongside konaks with buttressed terraces, carved moldings and louvered shutters. Some had been gleamingly restored. Others were frail. To me those derelict buildings breathed the romance of history, whispering "The present decays; the past remains."

It was a whisper I would hear often over the next few days. Buyukada enveloped me in the extraordinary life of a place whose everyday reality differed so delectably from my own.

We made our way toward the bright yellow Buyukada cathedral, the Aya Dmitri, and the beautifully maintained Hodegetria parish church, near the Fayton Meydani (buggy square). The Ecumenical Patriarchate in Istanbul keeps up the island's splendid churches and monasteries, with their polished silver-and-gold-trimmed icons, jewel-toned chandeliers, antique pulpits and Greek-speaking monks, who admit tourists (if they're in when you ring at the door).

We ducked into the churches only briefly, because Ted, weary of walking, was eager to start biking. Climbing aboard a buggy, we rode to the family's villa. Father, sons and I chose our steeds and pedaled uphill.

We had gone only a couple of blocks, dodging buggies and bicyclists, when Owen turned onto a lane where we found the ruined villa where Leon Trotsky once lived in exile. It was down the slope from a pasha's mansion that once served as a setting for a popular Ottoman-era soap opera filmed on the island (which needs no special effects to evoke a 16th-century air) and that now is being renovated by a developer.

We kept quiet, not sure we were allowed on the property; and then, there it was: the rose-brick shell of Trotsky's villa, rising roofless, with empty Gothic windows and a towering ornamental facade -- an opera set dropped in a wilderness. Suddenly we heard voices. Was it the police? No. It was a group of Swiss tourists, necklaced in cameras, emerging from the portico. One of them proudly declared, "I'm an old Trotskyist!"

We hit the road again, cycling past mares grazing on the shoulder.

A pilgrimage at center of island

It turns out that tourists are not the only travelers who venture to Buyukada. Every year on April 23, thousands of pilgrims of all faiths journey from Turkey, Greece, the Balkans and even Russia, making their way to the monastery of Aya Yorgi (St. George), which lies at the center of the island, atop Yucetepe, the island's highest peak. As part of an age-old fertility ritual, they climb the steep road, unwinding spools of thread and twining it around the greenery, from the base of the hill all the way up to the church at the summit.

We saw the signs of their recent pilgrimage when we hiked up to Yucetepe the next morning: The roadside was edged with tangled thread in every color, like a mile-long cat's cradle. At the top of the mountain, beside the church of Aya Yorgi and the breathtaking views of the islands to the northwest, we saw the pilgrims' hopes, written on paper, tied to the branches of trees.

But before I could sink into too somber a reflection on this mythic tradition, a band of students from Kazakhstan broke my reverie, rocketing down on bikes to Birlik Meydani with jubilant shrieks. The contradictory images thrilled and unsettled me; once again, Buyukada had a way of making me feel like a passenger in a time machine, with the year set on "shuffle."