Punalur is a city situated near the Kerala-Tamil Nadu border in the Kollam district of the southern Indian state of Kerala. It is situated on the banks of the Kallada River and derives its name from the Tamil words; punal, meaning 'water' and ooru, meaning 'city', literally, 'city of water'. It is about 45 kilometres (28 mi) north-east of Kollam and 75 kilometres (47 mi) north of Thiruvananthapuram. It is also known as the "Gateway of Western Ghats". It is the second-largest city in Kollam and the fifth largest in south Kerala, it is home to a paper industry with the Punalur Paper Mills, established in the 1850s, one of the first industries in Kerala and a pioneer in the industrial development of the state. Punalur become an important trading and transport centre between Kollam and Sengottai (Tamil Nadu) under the rule of the Travancore Kingdom. Steady progress by the Punalur Panchayat administration saw an upgrade to municipality status in 1972. Despite this elevation in status, Punalur still lacks the basic infrastructure to cope with an ever growing population and an influx of tourists and pilgrims. Oldest bridge in India is situated in Punalur. It is also the first motorable bridge in India, constructed in 1877.