Phra Phutthayotfa Chulalok Maharaj (Thai: , 20 March 1737 7 September 1809), personal name Thongduang (), also known as Rama I, was the founder of the Rattanakosin Kingdom and the first monarch of the reigning Chakri dynasty of Siam (now Thailand). His full title in Thai is Phra Bat Somdet Phra Paramoruracha Mahachakkriborommanat Phra Phutthayotfa Chulalok ( ). He ascended the throne in 1782, following the deposition of King Taksin of Thonburi. He was also celebrated as the founder of Rattanakosin (now Bangkok) as the new capital of the reunited kingdom.

Rama I was born from a Mon male line descent family, great grandson of Kosa Pan. His father served in the royal court of the Ayutthaya Kingdom, and had served King Taksin in wars against the Burmese Konbaung dynasty and helped him in the reunification of Siam. During this time he emerged as Siam's most powerful military leader. Thongduang was the first Somdet Chao Phraya, the highest rank the nobility could attain, equaled to that of royalty. In 1782, he took control of Siam and crowned himself as the monarch. The most famous event in his reign was the BurmeseSiamese War of 178586, which was the last major Burmese assault on Siam.

Bangkok, officially known in Thai as Krung Thep Maha Nakhon and colloquially as Krung Thep, is the capital and most populous city of Thailand. The city occupies 1,568.7 square kilometres (605.7 sq mi) in the Chao Phraya River delta in central Thailand and has an estimated population of 10.539 million as of 2020, 15.3 percent of the country's population. Over 14 million people (22.2 percent) lived within the surrounding Bangkok Metropolitan Region at the 2010 census, making Bangkok an extreme primate city, dwarfing Thailand's other urban centres in both size and importance to the national economy.

Bangkok traces its roots to a small trading post during the Ayutthaya Kingdom in the 15th century, which eventually grew and became the site of two capital cities, Thonburi in 1768 and Rattanakosin in 1782. Bangkok was at the heart of the modernization of Siam, later renamed Thailand, during the late-19th century, as the country faced pressures from the West. The city was at the centre of Thailand's political struggles throughout the 20th century, as the country abolished absolute monarchy, adopted constitutional rule, and underwent numerous coups and several uprisings. The city, incorporated as a special administrative area under the Bangkok Metropolitan Administration in 1972, grew rapidly during the 1960s through the 1980s and now exerts a significant impact on Thailand's politics, economy, education, media and modern society.

The Asian investment boom in the 1980s and 1990s led many multinational corporations to locate their regional headquarters in Bangkok. The city is now a regional force in finance and business. It is an international hub for transport and health care, and has emerged as a centre for the arts, fashion, and entertainment. The city is known for its street life and cultural landmarks, as well as its red-light districts. The Grand Palace and Buddhist temples including Wat Arun and Wat Pho stand in contrast with other tourist attractions such as the nightlife scenes of Khaosan Road and Patpong. Bangkok is among the world's top tourist destinations, and has been named the world's most visited city consistently in several international rankings.

Bangkok's rapid growth coupled with little urban planning has resulted in a haphazard cityscape and inadequate infrastructure. Despite an extensive expressway network, an inadequate road network and substantial private car usage have led to chronic and crippling traffic congestion, which caused severe air pollution in the 1990s. The city has since turned to public transport in an attempt to solve the problem, operating five rapid transit lines and building other public transit, but congestion still remains a prevalent issue. The city faces long-term environmental threats such as sea level rise due to climate change.