5 Best Sights in Turkey

The Catholic Church maintains its presence with a small sanctuary run by Capuchin monks. It is set in a garden on Kutlu Sokak, several winding blocks in from the river. Enter its small courtyard from the side street. You might recognize the image of the church bell, with the minaret of the Sermaye Mosque behind—it's on tourist office brochures as a symbol of religious harmony. Mass is usually held here every Sunday evening at 5 or 6 depending on the time of year; it's a good idea to call ahead and confirm.

Upon being kicked out of Ayasofya after the Turkish conquest of the city, the Greek Orthodox Patriarchate wandered among several churches before settling here in the Church of St. George in 1601. Rebuilt after a fire in 1720, the church is a relatively simple basilica, though the (rather dark) interior has a refined atmosphere. Sarcophagi with the remains of some famous Byzantine saints, a Byzantine-era patriarchal throne, and two very old mosaic icons on the right side of the elaborate iconostasis are considered the most noteworthy features of the church. The main front gate of the compound has been welded shut ever since Sultan Mahmud II had Patriarch Gregory V hanged from it in 1821 as punishment for the Greek revolt. This small church is theoretically the center of the Orthodox world, though some Turks would like to claim that it serves only the dwindling community of Istanbul Greeks.

This small but interesting monastery complex has two main churches and a refectory carved out of rock. The Archangelos Church, thought to date from the 11th or 12th century, has extensive, but blackened, frescoes (a flashlight is essential), including one on the wall facing the entrance that shows the Archangel Michael fighting Lucifer in a landscape that strongly resembles Cappadocia. The walls and ceiling of the nearby Stefanos Church are covered with colorful, almost contemporary-looking floral and geometric designs dating from the 7th or 8th century. The monastery's ever-present caretaker, Cabir Coşkuner, speaks some English and is happy to guide visitors around.

On the northern edge of town is Sen Piyer Kilisesi, or Saint Peter Church—a tiny cave high up on a cliff, blackened by centuries of candle smoke and dripping with water that seeps out of the rocks. According to tradition, this is where the apostle secretly preached to his converts and where they first came to be called Christians. Now operated as a museum, it is one of the oldest churches in existence; the facade you see, however, was added by the crusaders in the 11th to 12th century. The area around it was a cemetery in classical times, and there are numerous rock-cut tombs and tunnels.

A scrambly path leads up to the giant carved face of Charon, the legendary boatman who took the dead across the River Styx. Adventurous visitors can follow the valley just south to view a large section of the Byzantine walls, which also served as a bridge and dam. The church was declared a site of pilgrimage by Pope Paul VI, and the Catholic Church traditionally holds a religious service here on the 29th of June.

One of the most remarkable and odd structures in Istanbul (and that's saying a lot), this small neo-Gothic church looks like it's covered with elaborate stone carvings, but when you get up close, you realize that it's all cast iron. It was prefabricated in Vienna, shipped down the Danube on barges, and erected on the western shore of the Golden Horn in 1898. The then-flourishing Bulgarian Orthodox community in Istanbul was eager to have an impressive church of its own as a statement of its independence from the Greek Orthodox Patriarchate (the Ottoman Sultan had given the community permission to break away in 1870, but the first church built on the site had burned down). The Istanbul municipality announced in mid-2011 that the church—one of the few such surviving prefab cast-iron churches in the world—would undergo restoration. The building is set in neatly tended gardens by the waters of the Golden Horn.