Founded in the 7th century, Istanbul spans Europe and Asia and has the Bosphorus running through it. The silhouette of one of Istanbul's beautiful mosques at sunset. The silhouette of the Blue Mosque and the Hagia Sophia, two of Istanbul's top attractions. Built in the sixth century, the Hagia Sophia started life as a cathedral, was converted into a Mosque and is now a museum. The Hagia Sophia, as seen from the Topkapi Palace. The cavernous interior of the Hagia Sophia. 75 metres long and 70 metres wide, the Hagia Sophia was the world's largest cathedral for almost a millennium. One of the Hagia Sophia's restored mosaics. The central dome of the Hagia Sophia (aka the Church of the Holy Wisdom). When visitors think about Istanbul, they usually picture the Blue Mosque (also known as the Sultan Ahmed Mosque). The Mosque was built in the 17th century, during the reign of Sultan Ahmed I. Here are its cascading domes, as seen from the Hagia Sophia. Intricate stained glass in the Blue Mosque. The Blue Mosque's central dome is 23.5 metres wide. And has numerous chandeliers hanging from it. The entrance to the Topkapi Palace, built by Mehmed II in the 15th century. The Topkapi palace comprises a series of four courtyards. This is a picture of the third courtyard, which contains the Sultan's offices. An audience chamber used by the Sultan to dispense justice. The beautiful dome of one of the many chambers found in the grounds of the Topkapi Palace ... and another one. Stunning stained glass in the Topkapi Palace. The exterior of Istanbul's archaeological museum The Alexander Sarcophagus is one of the museum's most famous treasures. The underground Basilica Cistern, constructed in the 6th century during the reign of Emperor Justinian. The famous, and upturned, Medusa statue. Turkish lamps on sale in Istanbul's Grand Bazaar. The Galata Tower in Beyoglu, as seen from the Golden Horn. The Mibrah of one of Istanbul's lesser known mosques. The view over Istanbul from the Galata Tower A ship on the Bosphorus at sunset. The Galatasaray Museum, Istanbul.One of Istanbul's older trams is just part of the city's excellent public transport system.