Rama IV Road

This road was build since the year 1857 during the King Mongkut (Rama IV)'s reign, can be considered as the first real road in Thailand. It was built about four years before Charoen Krung Road in the case similarly to Charoen Krung Road. The road was built after a request made from the foreign merchants and businessmen, who basically said that they were having difficulty and also wasting time in travelling to trade in the capital. Therefore they set up their stores for trading goods at the top of Khlong Phra Khanong up till Bang Na area, and requested that the government dig up a shortcut for the canal starting at Bang Na all the way up till Khlong Phadung Krung Kasem which was another outer city moat during that time.

King Mongkut graciously ordered that a new canal be dug up in front of Phlan Phairi Rap Fort (around the Hua Lamphong area) cutting through the fields, up till Khlong Phra Khanong. Khlong Phra Khanong was also dug up future, to cut through and reach the Chao Phraya River. The soil dug up would be used to pave a road as long as the canal itself. The King graciously named it Khlong Thanon Trong (straight road canal), however, it has another name that Khlong Hua Lamphong. Whereas the road that ran along the bank of the canal was called various names by the community ranging from Thanon Trong, Thanon Hua Lamphong, and Thanon Wua Lamphong. In the year 1919 during the King Vajiravudh (Rama VI)'s reign, there was an announcement to change the name of Hua Lamphong Nok Road (Outer Hua Lamphong Road) which ran all the way from Charoen Krung and Luang Sunthorn Kosa Roads to Rama VI Road in memory of King Mongkut who had initially ordered to dig up the canal and construct this road.

In 1947 Khlong Hua Lamphong was drained to make way for an extension of the road. The Paknam Railway, Thailand's first railway line, followed the route of Rama IV Road from 1893 until it closed in 1960 due to under-use and increased road traffic. Several flyovers were added in the 1980s and 1990s to improve traffic flow.[1]

The MRT Blue Line snakes underneath Rama IV Road between Hua Lamphong MRT Station and Queen Sirikit National Convention Center MRT Station.

Bordering the road are the Hua Lamphong railway station, Wat Hua Lamphong, New Sam Yan Market, Lumphini Park and Rama VI Memorial Plaza, King Chulalongkorn Memorial Hospital and Queen Saovabha Memorial Institute, Thai-Japanese Friendship Flyover, Metropolitan Electricity Authority, and 3HD.

As of 2019 the real estate bordering the road, particularly a 3.5 kilometre section stretching from Sam Yan to Klong Toey intersection, has attracted property investments totaling 185 billion baht and more investment is forecast.[2]