Assumption Cathedral, Bangkok: built on a 17th-century treaty between a Siamese king and Louis XIV

On Oriental Avenue, in the Bang Rak district, a short way from the Chao Phraya river, the Assumption Cathedral is the seat of the Catholic archdiocese of Bangkok. The Catholic presence in Siam precedes the arrival of the French by a century: as early as 1553-54 two Portuguese Dominicans, Girolamo della Croce and Sebastiano de Cantù, founded three parishes at Ayutthaya with about fifteen hundred converts, before both were killed in 1569. Siam became an apostolic vicariate in 1662, entrusted in 1669 to the Foreign Missions of Paris. A treaty signed at Lopburi on 10 December 1685 between King Narai and Louis XIV allowed Catholic missionaries to preach throughout the kingdom, before the period ended in persecution and the imprisonment of Bishop Laneau. The first church on the present site was requested in 1809 by the French missionary Father Pascal and completed in 1821 under the reign of Rama II, financed largely by the Teochew Catholic businessman Low Khiok Chiang. The name of the architect is not documented. The present building, in Romanesque Revival style with two brick bell towers, was rebuilt between 1910 and 1919 on the initiative of the rector Father Colombet, who commissioned a French architect whose name is not recorded, and was consecrated on 15 August 1919 by Bishop René Perros. According to some sources, nearby buildings were damaged by Allied bombing in 1942, with consequences for the cathedral as well, although this detail comes from a single source. The archdiocese of Bangkok, erected as the apostolic vicariate of Siam in 1662 and raised to a metropolitan archdiocese on 18 December 1965, is led today by Archbishop Francis Xavier Vira Arpondratana, installed in the early part of 2025. Catholics in Thailand are estimated at about three hundred and eighty-eight thousand people, less than one per cent of the population of an overwhelmingly Buddhist country. According to the chronology kept by the cathedral, three generations of the Thai royal family have visited it: King Ananda Mahidol, together with the future king Bhumibol, then a prince, on 4 May 1946; the princesses Soamsawali and Bajirakitiyabha in 1995; and the then crown prince Vajiralongkorn, today King Rama X, in 2002. Pope John Paul II, visiting Thailand on 10-11 May 1984, and Pope Francis, on 22 November 2019, are both said to have come to this cathedral according to its official chronology, although this detail has not been found in an independent primary Vatican source. The Bang Rak district, where the cathedral stands, grew between the late nineteenth and the early twentieth century as the main foreigners’ quarter and commercial hub of Bangkok, home to the Portuguese and Chinese Catholic communities alongside European consulates and legations.