Hyderabad is the fourth most populous city of India with a total population of about 6.8 million. This capital of the state of Telangana, is located on the banks of the River Musi, a tributary of River Krishna at an elevation of 1657 ft in the Hyderabad district in the northern part of the Deccan Plateau. Majority of the population speaks Telugu. According to the data of the 2011 census, the literacy rate is 83 percent in the district and 36 percent of the total population is in the working age. Only 4 percent are employed in the agriculture sector, 3 percent in the household industry and the bulk 93 percent in services and industry which includes the entire gamut of activities ranging from Pharmaceuticals, Biotechnology, Information Technology, Trade and Commerce, Transportation, Storage, Communication, Real-estate, Retail, Banking, Insurance, Electrical and Engineering. Today, Hyderabad is the fifth largest contributor to Indias overall GDP. Industrialization began early under the Nizams in the late 19th century, helped by railway expansion that connected the city with major ports. Historically, the city has been a hub for arts and culture as patronized by the Nizams and emerged as the foremost centre of culture in India with the decline of the Mughal Empire. After the fall of Delhi in 1857, the performing artists particularly from the north and west of the India migrated to Deccan, resulting in a mingling of North and South Indian languages, cultures and religions, which has since led to a co-existence of Hindu and Muslim traditions, for which the city has become noted. Both Telugu and Urdu are official languages of Telangana. Deccani Paintings, Handicrafts, Jewelry, Zari-Zardozi embroidery and Kalamkari are the prominent crafts of this region. Hyderabads role in the pearl trade has given it the name "City of Pearls" and until the 18th century, the city was the only global trading centre for the Golconda Diamonds. Hyderabadi Biryani and Haleem carry the National Geographical Indications tag. Charminar, built in 1591, and situated on the east bank of the Musi River is the most recognized icon of Hyderabad city. To the Northeast lies the colorful Laad Bazaar and in the West lies the richly ornamented Mecca Masjid made of granite. The Golconda fort lies on the outskirts of the city, with its Persian Style Qutb Shahi Tombs and Secunderabad was developed by the British as a Cantonment. Iron Age sites that may date back to 500 BCE have been excavated in the region comprising modern Hyderabad and its surroundings that was known as Golkonda (Golla Konda or "shepherds hill").