Siddharthanagar, formerly and colloquially still called Bhairahawa, is a municipality and the administrative headquarter of Rupandehi District in Lumbini Province of Nepal, 265 km (165 mi) west of Nepal's capital Kathmandu. It is the closest city to Lumbini, the birthplace of Gautama Buddha, which is located 25 km (16 mi) to the west. The city borders the Indian city of Sonauli in Maharajganj district of Uttar Pradesh.

Gautam Buddha International Airport, also known as Bhairahawa Airport, is an international airport located in Siddharthanagar serving Lumbini in Lumbini Province, as well as the Butwal﹣Siddharthanagar urban agglomeration in Nepal. In May 2022, it became Nepal's second international airport, after previously only handling domestic services.