7 Best Sights in Istanbul, Turkey

Located in Balat, the city's historically Jewish district, Istanbul's oldest synagogue is believed to date from the 1430s, when it was founded by Jews from the town of Ohrid in what is today Macedonia. The synagogue was extensively restored in 1992 to the Ottoman baroque style of its last major reconstruction in the 17th century. The most interesting feature of this Sephardic place of worship is the boat-shape wooden bimah (reading platform), whose form is thought to represent either Noah's Ark or the ships that brought the Jews from the Iberian Peninsula to the Ottoman Empire in 1492. To visit, you must apply by email (preferred) or fax at least four business days in advance to the Chief Rabbinate (follow the directions on the website).

Upon being kicked out of Aya Sofya 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.

Muslim pilgrims from all over the world make their way to the brightly colored, tile-covered tomb of Eyüp Ensari (Ayyub al-Ansari)—a companion of the Prophet Muhammad who served as his standard-bearer—at this mosque complex on the Golden Horn. Ensari was killed during the first Arab siege of Constantinople (AD 674–78), and the eternal presence of a man so close to Muhammad makes this the holiest Islamic shrine in Turkey. His grave site was visited by Muslim pilgrims in Byzantine times and "rediscovered" during Mehmet the Conqueror's siege of Constantinople. After the conquest, Mehmet monumentalized the tomb and built a mosque, where investiture ceremonies were held for successive sultans. The mosque currently on the site was built after the original edifice was ruined in the 1766 earthquake. The plane-tree-shaded courtyards and large numbers of visitors imbue Eyüp Sultan Camii with a sense of peace and religious devotion not found in many other parts of this often frenetic city. A vast cemetery has grown up around the mosque. It's best to avoid visiting at prayer times.

The walls of Constantinople were the greatest fortifications of the medieval age and, although they were severely damaged by Sultan Mehmet II's canon in the siege leading up to the Ottoman conquest of the city in 1453, large sections still stand more or less intact. The walls were built in the 5th century after the city outgrew the walls built by Constantine, and they stretched 6½ km (4 miles) from the Sea of Marmara to the Golden Horn. The "wall" was actually made up of a large inner and smaller outer wall, with various towers and gates, as well as a moat. Parts have been restored, and you can even climb around on top; the easiest section on which to do this is near Edirnekapı, a short walk uphill from Chora.

Temporarily closed for renovation, the Chora Church, formerly a museum and now a mosque, contains dazzling mosaics and frescoes that are considered to be among the world's finest Byzantine artworks. Most of the mosaics, in 50 panels, depict scenes from the New Testament and date from the 14th century. They are in splendid condition, having been plastered over when the church became a mosque in the 16th century and not uncovered until the 1940s. "Chora" comes from the Greek word for countryside; the original church here was outside the city walls that were built by Constantine the Great, but at the beginning of the 5th century AD, Theodosius built new fortifications to expand the growing city, which brought the church inside the walls. The current edifice is believed to have been built in the 12th century. The easiest way to reach Kariye Camii is by taxi or by Edirnekapı-bound bus from Eminönu or Taksim Square. The tree-shaded café outside the mosque is a pleasant spot for lunch before you trek back into town.

Housed on the grounds of an Ottoman-era shipyard on the shore of the Golden Horn, and in an adjacent foundry where anchors were cast for the Ottoman fleet, this museum complex was founded by one of Turkey's leading industrialists. The wonderful, eclectic collection includes aircraft, boats, a submarine, a tank, trucks, trains, a horse-drawn tram, motorcycles, antique cars, medieval telescopes, and every type of engine imaginable. Along with the many vehicles and machines, interactive displays on science and technology, as well as recreations of a sawmill and a 1920s olive oil factory, are of special appeal to children. There are several on-site food and beverage venues, including Café du Levant, a Parisian-style bistro with Art Nouveau furnishings, and the waterfront Halat Restaurant. Take a Golden Horn ferry, a bus from Şişhane, or a taxi to get here.

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.