Located in Southeast Asia, the Republic of Singapore is a city-state linked  to the Malaysian mainland by a 2/3 mile (1.1 kilometers) long causeway that carries a road and railway. Known as the Lion City, Singapore is a modern metropolis with one of the world's busiest ports. At the same time, the small tropical island has retained many elements of its colonial past. The multiethnic nature of the population provides a rich and varied cultural, religious, and linguistic heritage.