From Galata Karaköy ferry terminal every half hour until after 11pm. Fishing boats against backdrop of Old City lights, ferry searchlights sweeping open water.
From Karaköy (over Galata Bridge from Eminönü) to Kadıköy. On the other side walk around and check out the restaurants if you have time, before hopping on the return ferry.
From Eminönü to Üsküdar is a shorter trip. Restaurants and cafes beckon here too, as does the waterside promenade beside Maiden's Tower (Kız Kulesı), a pleasant summer walk.
Istanbul Deniz Otobüsleri (IDO) / Şehir Hatları are Istanbul’s official sea bus, fast ferry and regular ferry companies, with three options: Short Circle Bosphorus Cruise, Full Bosphorus Cruise and the Full Bosphorus Cruise by Night.

The Galata Tower (Christea Turris in Latin) 66.9 meter (219 ft) stone tower was built by the Genoese, completed in 1348 at their citadel in the Galata/Karaköy quarter of Istanbul. Chiristian prisoners of war were executed here after the conquest of Istanbul by Fatih Sultan Mehmet.

in 1630-1632, Hezarfen Ahmet Çelebi is said to have glided on artificial wings from the tower across the Bosphorus to the slopes of Üsküdar on the Anatolian side, about six kilometres distant. Beginning in 1717 the Ottomans used the tower to spot fires in the city. The French panorama painter Pierre Prévost drew his 1818 "Panorama de Constantinople" from the top of the tower, exhibited in Paris in 1825.

After the most recent restoration in the 1960s, the wooden interior of the tower was replaced with concrete structure, commercialized and opened to the public. Still among the city's most striking landmarks, the cone-capped cylinder dominates the skyline and now houses a Turkish/Ottoman restaurant and showclub at it's apex, with panoramic views of Old Istanbul and beyond. From Taksim take a walk down İstiklal, and to the end of Galip Dede Caddesi.

Of three buildings at this Orthodox patriarchal basilica site (first dedicated in 360 by Emperor Constantius II), two burned during riots of 404 and 532. The current structure was ordered built by Justinian I, larger and more majestic than its predecessors. Materials came from around the empire: Hellenistic columns from the Temple of Artemis at Ephesus, Egyptian stone, green marble from Thessaly, Bosporus black stone, and Syrian yellow stone. Over 10,000 men labored here. After the inauguration, on December 27, 537, it was the largest cathedral for 1,000 years. Justinian proclaimed "Solomon, I have outdone thee!"  Mosaics were completed under Justin II (565–578). Seat of the Orthodox patriarch of Constantinople, it was a sanctuary for persecuted outlaws, and the principal Byzantine imperial ceremonial site.

Frequent earthquakes caused partial collapses in 558, 869, and 989. Each time the building was restored. Pictures and statues were removed during the Byzantine Iconoclasm. Between 726 and 842, under emperors Leo the Isaurian and Theophilus, the veneration of imagery was forbidden, as it would be during centuries under Islam.

The church was ransacked and desecrated by Fourth Crusade Latin Christians. Relics sent to churches in the West may now be seen in various museums. During the 1204-1261 occupation the church was a Roman Catholic cathedral. In 1261 the Byzantines returned to find it dilapidated. Emperor Andronicus II had new buttresses built in 1317, but cracks appeared after an 1344 earthquake, and parts of the building collapsed in 1346, closing it until 1354.

In 1453 Ottoman troops of Mehmed II made the Hagia Sophia a focal point of their pillage, desecrating and looting it. Byzantines taking sanctuary were slaughtered or enslaved. Converted to the Aya Sofya Mosque, it was to be the principal mosque of Istanbul for almost 500 years; a model for others such as the Sultan Ahmed Mosque, and the Şehzade Mosque.

Another earthquake in 1509 collapsed a minaret, restored under Selim II (1566–1574) by the great architect Mimar Sinan, one of the first earthquake engineers. He added four great minarets seen today, along with Selim's mausoleum. Sultan Ahmed III (1703–1730), had plaster renovated, helping to preserve mosaics that would otherwise have been sold as talismans to visitors. Restorations by Mahmud I in 1739 added a medrese (now the museum library), a soup kitchen for the poor, a library, and an ablutions fountain.

The most famous Aya Sofya restoration, by Sultan Abdülmecid, was completed in 1849 by eight hundred workers under the Swiss-Italian architect brothers, Gaspare and Giuseppe Fossati. Mosaics were also cleaned, old chandeliers replaced, and gigantic medallions hung, inscribed by calligrapher Kazasker Mustafa İzzed Effendi with the names of Allah, the Prophet Muhammad, caliphs Abu Bakr, Umar, Uthman and Ali, and Mohammed's grandsons, Hassan and Hussain. With ceremonial pomp the mosque re-opened in July, 1849.

In 1935 the building became a museum with the establishment of the Republic of Turkey under President Mustafa Kemal Atatürk. With carpets removed marble floor decorations such as the Omphalion appeared for the first time in centuries, and plaster-covered mosaics were revealed.

For Tuesday-Sunday tours see the website:

Over one million objects, representing almost all of eras and civilizations in world history, housed in the Archaeological Museum (main building), the Museum of the Ancient Orient, and the Museum of Islamic Art in the Topkapı Palace outer gardens.

The collection includes: the ornate sarcophagus of Alexander, depicting scenes from the life of Alexander the Great; the Tiled Pavilion, one of the city's oldest Ottoman structures, with fine ceramics; the Kadesh Peace Treaty of 1269 BC, signed between Ramesses II of Egypt and Hattusili III of the Hittite Empire, the oldest known peace treaty in the world; Turkish, Hellenistic and Roman artifacts; ancient Greek statues; early Anatolian, Mesopotamian, Arabian and Egyptian artifacts; Ottoman coins, seals, decorations and medals; the Troy exhibit; the Lycian tomb; Mother-Goddess Cybele and votive stelai; busts of Alexander the Great and Zeus....

Open Tuesdays-Sundays 9am-7pm.

Home to generations of sultans and their families closeted in the harem, around a Turkish bath (be sure to pay the extra ticket for the harem). Sea of Marmara, Bosphorus and Golden Horn vistas, verdant courtyards. The museum collection includes: holy relics of the Muslim world, Muhammed's cloak and sword; 10,700 pieces of Chinese porcelain and 14th-century Longquan celadon; Japanese Imari porcelain; Blue-and-White and Imari porcelain from Vietnam, Thailand and Persia; arms and armour.

The Imperial Treasury has a vast collection of works of art, jewelry, and the Topkapı Dagger - with golden hilt ornamented with three large emeralds, topped by a golden watch with an emerald lid. The dagger's golden sheath is covered with enamel and diamonds. Also: Ottoman miniatures of which only 100 of 10,000 are on display at any one time; the walnut throne of Ahmed I, inlaid with nacre and tortoise shell, built by Sedekhar Mehmed Agha; a jade bowl present from Czar Nicholas II of Russia; the Spoonmaker's Diamond, set in silver, surrounded with 49 cut diamonds.

The palace was the primary royal residence of the Ottoman Sultans for approximately 400 years, and a setting for state occasions and royal entertainments, consisting of four main courtyards and many smaller buildings. At its peak, the palace was home to as many as 4,000 people, with entry and exit tightly controlled, and strict, ceremonial, codified daily life for those who lived within the walls.

Tours: Tuesdays - Sundays 9am-6pm (the harem closes at 5pm). See the Wikipedia article, and the official website below for more information: