Pope Pius IX wanted a Catholic university in Brussels, but the only Catholic university in the country was forty kilometres east in Leuven. The compromise, in 1858, was modest: a philosophy department tucked inside a diocesan secondary school on the rue du Marais, preparing young men for the higher liberal arts certification they needed to study law elsewhere. That small department was the seed of what became Saint-Louis University, Brussels - and the long, patient story of how it grew from one corridor of a Jesuit school into a five-faculty university, only to merge itself out of independent existence in 2023.
When the Catholic University of Belgium moved from Mechelen to Leuven in 1835, it left behind empty buildings and a problem. Brussels had no Catholic institution of higher learning, and the clergy wanted one. The solution arrived in stages. First came the Ecole de Commerce et d'Industrie in 1838, then its transfer to Brussels in 1858, where it took the name Institut Saint-Louis and added a philosophy department. Belgian law of the period required would-be law students to hold a liberal arts certification, and the Catholic philosophy professors of the Institut Saint-Louis were happy to provide it. Year by year, that one department added subjects and students. In 1891, with the recognition of non-state universities, the institution earned the status of an autonomous "free" university - a status it would hold for the next 132 years.
In 1925, the university founded HEC Saint-Louis, Belgium's first independent business school, and in the same year established the School of Philosophical and Religious Sciences. The man behind the school was Desire-Joseph Mercier, the cardinal of Mechelen who had earned international fame for his open defiance of the German occupiers during the First World War. Mercier wanted a place where Catholic philosophy could engage the major currents of modern European thought without flinching. The chairs his school has hosted since read like a syllabus of twentieth-century continental philosophy: Paul Ricoeur, Michel Serres, Jacques Lacan, Tzvetan Todorov, Alain Touraine, Pierre Bourdieu, Jean-Luc Nancy. Few of them were Catholic. None of them were excluded for it. That was the point.
The main campus sits on the northern edge of the historic inner city, opposite the Botanical Garden of Brussels across the small ring road. The address is rue du Marais - or Broekstraat in Dutch, because in Brussels every street name is bilingual whether you like it or not. The street has a curious through-line: every Catholic higher-education project that splintered off from Saint-Louis over the decades ended up nearby. The Dutch-speaking department left in 1973 to become UFSAL, which became K.U.Brussel, which became Hogeschool-Universiteit Brussel, which reorganised in 2013 into the KU Leuven campus Brussel and the vocational college Odisee. All of them are still on rue du Marais. So is the ISC Saint-Louis, the descendant of the original 1925 business school. Walk the length of the street and you walk through a century and a half of Belgian Catholic education, fragmenting and reassembling under different names.
By the early 2010s, Saint-Louis had a problem: its student body had tripled in fifteen years to over four thousand, and the buildings on rue du Marais could not absorb them. In 2015 the university bought the Ommegang building, a former Belfius bank office block next door, and converted it into lecture theatres, a new library, a 1,300-person multipurpose hall, and roughly a hundred student apartments. The new auditorium became the largest the institution had ever owned. When the rectors of Saint-Louis and Louvain inaugurated the building together in May 2018, they were already negotiating something bigger: the full merger of their two universities. The renovated campus, doubling Saint-Louis's surface area from 25,000 to 47,000 square metres, was being prepared not for an independent future but for a new identity as a Brussels campus of a much larger institution.
In May 2017, the boards of Saint-Louis and the University of Louvain each voted with roughly 90 percent in favour of merging. Both institutions began using the name UCLouvain in September 2018, and the legal merger was completed in 2023. Saint-Louis University, Brussels became UCLouvain Saint-Louis Bruxelles - a campus, not a university. For an institution that had spent 132 years defending the autonomous "free" status it won in 1891, this was a strange kind of ending. It was also a calculated survival. Brussels was unwilling to support five separate French-speaking universities; the merger consolidated the Catholic ones into a single Brussels-Wallonia network. The rue du Marais campus kept teaching philosophy, law, economics, and translation, just under a different letterhead. The Marie Haps Faculty of Translation and Interpreting, added in 2015, continues to operate from its buildings on rue d'Arlon, directly across from the European Parliament - a faculty in one quarter, a parliament in the other, separated by a single street and several languages.
Saint-Louis University's main campus is at 50.854 N, 4.361 E, on the northern edge of central Brussels opposite the Botanical Garden, directly inside the small ring road. The Marie Haps faculty is at the European Parliament, about 1.5 km southeast. Both sit within 4 km of Brussels Central (50.846 N, 4.357 E). Brussels Airport (EBBR) is 12 km northeast; Brussels South Charleroi (EBCI) is 46 km south. Brussels Class C terminal airspace covers the area; expect Brussels TMA traffic and frequent low-level approaches to EBBR runway 25L/07R.