Malaysia is ranked 9th in the world for tourist arrivals. In an effort to diversify the economy and make Malaysia's economy less dependent on exports, the government pushed to increase tourism in Malaysia. As a result, tourism has become Malaysia's third largest source of foreign exchange income, and accounted for 7% of Malaysia's economy as of 2005. The Petronas Towers, also known as the Petronas Twin Towers are twin skyscrapers in Kuala Lumpur, Malaysia. According to the Council on Tall Buildings and Urban Habitat (CTBUH)'s official definition and ranking, they were the tallest buildings in the world from 1998 to 2004 and remain the tallest twin towers in the world. Batu Caves (Tamil) is a limestone hill that has a series of caves and cave temples in Gombak, Selangor, Malaysia. Kuala Lumpur Bird Park is a 20.9-acre (8.5 ha) public aviary in Kuala Lumpur, Malaysia. It is a popular tourist attraction in the country, receiving an annual average of 200,000 visitors. The Kuala Lumpur Tower is a communications tower located in Kuala Lumpur, Malaysia. Its construction was completed on 1st March 1995. It features an antenna that increases its height to 421 metres (1,381 feet) and is the 7th tallest freestanding tower in the world.