King Prajadhipok ascended the throne in 1925 and abdicated in 1935, reigning for nine years during a period of global economic depression following the First World War. To address financial hardship in Siam, he reduced royal and military budgets, dissolved some government agencies, and dismissed many civil servants to ease the nation’s expenditures. These austerity measures contributed to discontent that ultimately led to the 1932 revolution, after which the king granted Siam its first constitution.

His reign was notable for important achievements in governance, culture, education, and urban development. He established the Privy Council, enacted laws to regulate public utilities and finance, introduced the municipal administration system, and supported higher education reforms that raised university standards to degree level. He founded the Royal Institute, oversaw the publication of the Siam Rat Tripitaka — a complete Thai-script edition of the Buddhist canon — and promoted cultural and intellectual development.

In 1932, when Bangkok marked its 150th anniversary, he organised grand celebrations rooted in royal tradition while ensuring practical benefits through the construction of enduring landmarks. These included the Phra Phuttha Yodfa Bridge (Memorial Bridge) and the Sala Chalermkrung Royal Theatre. The bridge, the first road bridge over the Chao Phraya River, reflected modern Western-influenced architecture and advanced engineering technology, featuring a bascule mechanism that allowed it to open and close. Its construction facilitated urban expansion and economic growth.

The Sala Chalermkrung Royal Theatre was built as a large, modern cinema equipped with air conditioning — a rare technological feature at the time — and hosted screenings of Western films. This venue introduced Western-style entertainment to Thai society and helped modernise cultural life. Both projects demonstrated the king’s vision of combining modernity with enduring benefit to Bangkok.