Galata Tower Istanbul, one of the oldest and most beautiful towers in the world, was constructed in 528, during the reign of the Byzantine Empire. It was used in the 13th century by the Genoese. From the top there is a marvelous panaroma of the Golden Horn, Bosphorus, Topkapi Palace, Imperial Sultanahmet Mosque - Blue Mosque, Haghia Sophia, Leanders Tower (Maidens Tower), old city Sultanahmet.

Tunel is the oldest and most probably the shortest underground railway in the world. It was built in 1873 by French engineers and has a length of about 500 meters. Most foreign businessmen and all the foreign embassies moved to Beyoglu Istanbul. However, business, offices and companies stayed in Karakoy (Galata). To avoid climbing up and down this underground was built. You can't get out at the wrong station, for there're only two, one in Karakoy (Galata) and one in Beyoglu at Tunel Square end of Istiklal Street.

Museum of Divan Literature Istanbul is originally a Galat Mevlevihanesi - Whirling Dervish Hall and still preserved as such. Whirling dervishes took their name from the great Sufi poet and mystic, Calaleddin Rumi (1207-73), with their major aim being the mystical communication with God. But for the acolytes of Calaleddin Rumi, it was more than just a matter of spinning for God; the entire 'sema' (ceremony) involved chants, prayers and music before the Mevlevi 'tarakat' whirled themselves into a trance-like union with God. The museum is open daily, except Tuesdays.

ISTANBUL MOSQUES
Imperial Sultanahmet Mosque (Blue Mosque): Across from Hagia Sophia stands the supremely elegant Imperial Sultanahmet Mosque with six minarets. Built between 1609 and 1616 by the architect Mehmet, the building is more familiarly known as the Blue Mosque because of its magnificent interior paneling of blue and white Iznik Tiles.
Imperial Suleymaniye Mosque:Considered the most beautiful of all imperial mosques in Istanbul, it was built between 1550 and 1557 by Sinan, the renowned architect of the Ottoman Empire's golden age. It was in the gardens of this complex that Suleyman and his wife Hurrem Sultan (Roxelane), had their mausolea built, and near here, also Sinan built his own tomb.

ISTANBUL MUSEUMS
Topkapi Palace Museum: When Sultan Mehmet the Conqueror took Istanbul in 1453, he first ordered the construction of a new palace for this new Ottoman capital, on a site in the district of Beyazit where Istanbul University stands today. Topkapi Palace was home to all the Ottoman sultans until the reign of Abdulmecid I (1839-1860), a period of nearly four centuries. After the establishment of the Republic in 1923 it was extensively renovated and transformed into a museum, and ever since has been one of Istanbul's most popular sights. Since Topkapi Palace is so large, only some sections are open to the public. Harem, there are rooms occupied by the black eunuchs, concubines, the sultan's mother and the sultan himself. The most fascinating aspect of the Harem was the cloak of secrecy over life here. Virtually none of its inhabitants had the freedom to go out at will, and equally almost no one from the outside world was ever admitted. Harem section can be visited only by a guided tour and tickets should be purchased separetely. Topkapi Palace Museum is open everyday except Tuesday, 9:00 to 17:00.
Hagia Sophia Museum: The Basilica of Hagia Sophia, now called the Ayasofya Museum, is unquestionably one of the finest buildings of all time. Built by Constantine the Great and reconstructed by Justinian in the 6th century. (open every day except Monday)
Istanbul Archeological Museum: It is just inside the first court of Topkapi Palace. The museum of the Ancient orient displays artifacts from the Sumerian, Babylonian, Assyrian, Hatti and Hittite civilations. (Open every day except Monday)
Yerebatan Cistern: Near Hagia Sophia is the 6th century Byzantine cistern known as the Yerebatan Cistern. 336 massive Corinthian columns support the immense chamber' s fine brick vaulting. (Open every day)
Kariye Museum:The 11th century church of "St. Savior" in the Chora complex is, after Hagia Sophia, the most important Byzantine monument in Istanbul. The walls are decorated with superb 14th century mosaics.(Open every day except Wednesday)

Other Touristic Places To See In Istanbul
Maiden's Tower: Also known as Leander' Tower, is one of the most romantic symbols of Istanbul. On a tiny island at the entrance to Istanbul's harbor, the first tower constructed in the 12th century.
Grand Bazaar - Covered Bazaar: One could only visit Istanbul for the shopping alone. The Grand Bazaar in the old city is the logical place to start. Charming souvenirs and gifts can be selected from among Turkish crafts, the world-renowed carpets, gold jewelry, brillant handpainted ceramics. The Old Bedesten offers a curious assortment of antiques.
Spice Bazaar, next to the Yeni Mosque at Eminonu, transports you to fantasies from the mystical East. Sultanahmet has become another shopping center in the old city. The Bazaar of Istanbul Arts, The Arasta (Old Bazaar) of the Sultanahmet Mosque a thriving shopping arcade makes both shopping and sightseeing Istanbul very convenient.