Looking at the Bangkok of today, it is difficult to imagine that only 400 years ago it was small village on the west bank of the Chao Phraya surrounded by wild plum trees. It wasn't until 1782 that King Rama moved the capital city to Bangkok and began work on the Grand Palace and the Temple of the Emerald Buddha. These amazing structures were completed by 1785. In addition, Rama dug defensive moats,  built canals, constructed temples and erected city walls.

By the 1850's Bangkok had become known as the "Venice of the East", with its extensive canal system. At this time there were very few roads, rather Bangkok was a city with a large network of water-roads thus having a large percentage of inhabitants living in floating houses.

Here is a link to a Brief History of Bangkok