Charoen Krung Road (, ) is a major road in Bangkok and the first in Thailand to be built using modern construction methods. Built during 1862–1864 in the reign of King Mongkut (Rama IV), it runs from the old city centre in Rattanakosin Island, passes through Bangkok's Chinatown, continues into Bang Rak district, where it formerly served the community of European expatriates, and ends in Bang Kho Laem. Construction of the road marked a major change in Bangkok's urban development, with the major mode of transport shifting from water to land. Charoen Krung Road was Bangkok's main street up to the early 20th century, but later declined in prominence. It is still home to many historic buildings and neighbourhoods, which are beset by changes as extension of the underground MRT is poised to drive new development. History Until the mid-19th century, the primary means of transport in Bangkok (and Siam in general) was by boat. This began to change as the country opened up to Western ideas and influences, and underwent modernization during the reign of King Mongkut (Rama IV, r. 1851–1868). The signing of the Bowring Treaty in 1855 marked the beginning of increasing Western political and economic influence, and many foreigners set up diplomatic missions, trading companies and residences on the east bank of the Chao Phraya River, just beyond the newly expanded city limits marked by Phadung Krung Kasem Canal, which had been dug in 1851. On 19 August 1861, Western consuls, complaining of ill health due to a lack of roads in which they could travel by horse-drawn carriage, requested that the King build a new road on the east side of the river behind the consulates and businesses. The King agreed to the request, and ordered the construction of a new system of roads. The first, which would serve the European district, was begun in 1862 and officially opened to traffic on 16 March 1864. At the time, roads were not officially named, and the road became known as Thanon Mai () or New Road. King Mongkut later gave it the name Charoen Krung, which means "prosperous city" or "prosperity of the city". The road, constructed in two phases, runs roughly parallel to the Chao Phraya River in a southerly direction from the city centre. The first section ran from the old city moat, crossed Phadung Krumg Kasem Canal, and continued through the European district