Rumelian Fortress (Rumeli Hisarı): It is a fortress located in Sarıyer on the European side. It was built by the Ottoman Sultan Mehmed II between 1451 and 1452, before he conquered Constantinople. The three great towers were named after three of Mehmed II's viziers, Sadrazam Çandarlı Halil Pasha, who built the big tower next to the gate, Zağanos Pasha, who built the south tower, and Sarıca Pasha, who built the north tower.
Anatolian Fortress (Anadolu Hisarı): The fortress is situated on the Asian shore of the Bosphorus, the sole outlet of the Black Sea, and it was built by Sultan Bayezid in 1390-91. Next to it there is a stream running into the sea. Together with the Rumelian Fortress on the opposite side, it ensured full control over the traffic in the Bosphorus. This small fortress creates a picturesque scene with the old wooden houses leaning on its walls and its green surroundings. The Kanlıca district, a little further up the Bosphorus, is famous for its seaside cafes and yogurt. The Asian towers of the Fatih Bridge rises in this district.
Hagia Sophia (Ayasofya): is a former Greek Orthodox patriarchal basilica (church), later an imperial mosque, and now a museum (Ayasofya Müzesi) in Istanbul, Turkey. From the date of its construction in 537 until 1453, it served as an Eastern Orthodox cathedral and seat of the Patriarchate of Constantinople, except between 1204 and 1261, when it was converted to a Roman Catholic cathedral under the Latin Empire. The building was a mosque from 29 May 1453 until 1931. It was then secularized and opened as a museum on 1 February 1935.
The Bosphorus (Boğaziçi): is a strait that forms part of the boundary between Europe and Asia. The Bosporus, the Sea of Marmara, and the Dardanelles strait to the southwest together form the Turkish Straits. The world's narrowest strait used for international navigation, the Bosporus connects the Black Sea with the Sea of Marmara (which is connected by the Dardanelles to the Aegean Sea, and thereby to the Mediterranean Sea). It is one of the defining characteristics of Istanbul making it one of the most beautiful cities in the world.
The Basilica Cistern (Yerebatan Sarnıcı): The city's most unexpectedly romantic attraction, the Basilica Cistern, offers an insight into the complicated system that once brought drinking water into Istanbul from Thrace. Constructed in the sixth century and then forgotten for centuries, the cistern that once stored the water has been fitted with lights and music. Fish flitter around the bases of the 336 columns that support the ceiling. Don't miss the upside-down head of Medusa that forms the bottom of one column, proof that Byzantine builders saw Roman relics as little more than reusable rubble.
Topkapı Palace: If there is one absolute must-see in Istanbul, it has to be the Topkapı Palace, home to generations of sultans and their wives, who were closeted in the famous harem. A collection of lush green courtyards and delicate kiosks, the Topkapı boasts a treasury to put the crown jewels in the shade, as well as views to die for over the Sea of Marmara, Bosphorus and Golden Horn. The secretive harem – really just the family quarters – is a warren of lushly-tiled rooms wrapped round a gem of a Turkish bath. Try to visit on a day when no cruise ship is in town to avoid the worst of the crowds.
Blue Mosque (Sultan Ahmet Camii): Facing Aya Sofya across a small park and mirroring its domed silhouette, the early 17th-century Blue Mosque is one of only a handful of mosques in the world to boast six minarets. Is it really blue? Well, not noticeably, although all the walls are papered with fine İznik tiles. To view it as the architect, Sedefkar Mehmed Aga, originally intended, enter via what looks like the side entrance from the Hippodrome. Afterwards, pop your head into a building the size of a small mosque on the corner of the complex. This houses the tomb of Sultan Ahmed I, the man who gave his name to both the mosque and the neighborhood.
Istanbul Archaeology Museum: Walk to Istanbul's three-in-one equivalent of the British Museum via the grounds of Topkapı Palace or through Gülhane Park. If time is tight, go straight to the large porticoed building housing the glorious sarcophagus of Alexander which depicts scenes from the life of Alexander the Great in vivid 3D. Kids will love the model Trojan Horse in the children's section. Then pop into the lovely Tiled Pavilion, one of the city's oldest Ottoman structures, beautifully restored to show off its finest ceramics. Finally, catch a glimpse of a peace treaty from 1269 BC preserved in the part of the museum nearest to the gate.
Turkish and Islamic Arts Museum: Housed in what was originally the palace of Ibrahim Pasha, a favorite grand vizier of Suleiman the Magnificent, and overlooking the Hippodrome where Byzantine lovers of chariot racing once brought the same passion to their sport as modern Turks do to football, this museum houses a magnificent collection of gigantic carpets from all over the country. Its basement features reconstructions of everything from a fully-fitted nomad tent to a grand interior from a 19th-century Bursa mansion. Don't leave without trying a thick black Turkish coffee in the pretty cafe in the grounds.
Süleymaniye Mosque: Unmissable as you stand on the busy Galata Bridge and look up at the city's historic skyline is the mosque designed by the great Ottoman architect Sinan for Suleiman the Magnificent. Newly restored to its original splendor, it is generally regarded as the finest of the 42 surviving mosques he designed for Istanbul. Unusually, it retains much of the original complex of social service buildings that came attached to it, including several madrasahs, a hospital, a library and a Turkish bath.
Galata Tower (Galata Kulesi): Istanbul is a city that cries out to be viewed from on high, and you can get a bird's-eye view of everything from the balcony at the top of the Galata Tower in Beyoğlu, the modern part of old Istanbul that, in pre-Republican days, was home to the city's foreign residents. Built in 1348, the tower once formed part of a sub-city belonging to the Genoese that stretched right down to the Bosphorus. In a footnote to aviation history, it was from this tower that Hezârfen Ahmed Çelebi flew across the Bosphorus from Europe to Asia in 1638, thus inaugurating the first ever intercontinental flight.
Taksim Square (Taksim Meydanı): Taksim is the heartbeat of Istanbul nightlife and a main tourist attraction during the day. Closed off to most traffic, Taksim is wall-to-wall restaurants, stores, bars, specialty shops and more. Be sure to check out the Tunnel (Tünel).
NOTE: Taksim is the main location for protests in Istanbul and as such please take caution at times.
Dolmabahçe Palace (Dolmabahçe Sarayı): located in the Beşiktaş district of Istanbul, Turkey, on the European coastline of the Bosphorus strait, served as the main administrative center of the Ottoman Empire from 1856 to 1922. The palace commands a nice view right on the Bosphorus and its gardens are very pretty, especially in spring and summer. The founder of Turkey, Mustafa Kemal Ataturk passed away in this palace on November 10, 1938 at 9.05 AM.
The Grand Bazaar (Kapalıçarşı): It is one of the largest and oldest covered markets in the world, with 61 covered streets and over 3,000 shops that are always filled with crowds who not only come to shop but to window-shop carpets, jewelry, leathers, handcrafts, home decoration items and many more.
Spice Bazaar (Mısır Çarşısı): It is one of the largest bazaars in the city. Located in the Eminönü quarter of the Fatih district. This bustling marketplace was constructed in the 1660s as part of the New Mosque complex, with rents from the shops going to support the upkeep of the mosque and its charitable activities. It was called the Egyptian Market because it was famous for selling goods shipped in from Cairo.