The campus of Chulalongkorn University in Bangkok occupies an area of 637 rai (101.9 ha; 252 acres) in the city centre's Pathum Wan District. It accounts for just over half of the 1,153 rai (184.5 ha; 456 acres) of land owned by the university, the rest of which is commercially developed or used by other institutions. The campus sits on what was originally royal land surrounding Windsor Palace, granted for the university's use at its foundation in 1917 by King Vajiravudh. Ownership of the land was transferred to the university by an Act of Parliament in 1939.
At the university's establishment, the campus area consisted mostly of open fields. The first dedicated permanent structure, the Administration Building (now Maha Chulalongkorn Building), was completed in 1921. It was followed in the next three decades by several historic buildings, mostly designed by Phra Sarotrattananimman and showing increasing modern influence, reflecting the country's transition to constitutional monarchy. Many more buildings were built in the second half of the 20th century, and multiple high-rises have been erected since the 2000s. Buildings are now spread throughout most of the university campus, interspersed by green areas of planted groves and lawns, especially the main lawn in front of the Monument of King Chulalongkorn and King Vajiravudh, which forms the campus's central feature.
The university owns most of the land bounded by Rama I Road to the north, Henri Dunant Road to the east, Rama IV Road to the south and Banthat Thong Road to the west. The campus is bisected by Phaya Thai Road, with most of the faculties located on the east side and supporting facilities, residences and administration offices on the west. The academic area is bounded by commercial areas and neighbourhoods to the north, west and south.