Tourism in Turkey important tourism spots not only in Turkey but also in the world. There are thousands of hotels and other tourist-oriented industries in the city, catering to both vacationers and visiting professionals. Turkey's largest city and metropolis and a leading global city, Istanbul, has a number of major attractions derived from its historical status as capital of the Byzantine and Ottoman Empires. These include the Sultan Ahmed Mosque (the "Blue Mosque"), the Hagia Sophia, the Topkapı Palace, the Basilica Cistern, the Dolmabahçe Palace, the Galata Tower, the Grand Bazaar, the Spice Bazaar, and the Pera Palace Hotel. Istanbul has also recently
Galata gas field majority of the development project work was undertaken in 2003 and 2004. This included: Production from the Galata gas field commenced in June 2004 once all the infrastructure was in place and fully commissioned. The total proven reserves of the Galata gas field prior to production was around 75 billion cubic feet (Bcf). At peak production the field provided more than 16% of Bulgaria's domestic gas needs. Three additional satellite fields located to the East of the Galata gas field were discovered by Melrose. These were the Kaliakra gas field discovered in 2007, the Kavarna gas field discovered in 2008