The Library is housed in a partially listed former bank building at number 57, rue Montagne aux herbes potagères. It was constructed in 1872 on behalf of the Union du crédit de Bruxelles following the blueprint of renowned architect Désiré De Keyser. Another Brussels landmark to his credit is the huge synagogue on rue de la Régence.
Taken over in 1971 by the United California Bank, the building later came into the National Bank's possession. In 1994, the Patrimoine monumental de la Belgique (Monumental Heritage of Belgium) described the "remarkable interior décor of the bank (…), preserved as it was originally (…)" as "certainly the last remaining example in Brussels of the inside of a bank from that era". Yet the building had suffered badly from neglect, despite its partial listing in 1984. Its restoration, engineered by the National Bank of Belgium and under the supervision of the Brussels-Capital Region's Commission des monuments, sites et fouilles (Royal Commission for Monuments, Sites and Excavations) was both lengthy and meticulous.
At the end of a long corridor leading to the huge hall, abundant light is brought into the building through an attic window placed at a height of 18 metres. A large staircase, decorated with impressive bronze lamps, leads to a gallery that overlooks this area as well as the counter room which is located under an oval skylight. The original décor had been entrusted to a Frenchman called Georges Houtstont, who also worked on the National Bank's Hôtel du Gouverneur, on rue du Bois sauvage, several years later. The rather discreetly decorated stuccos and sandblasted glass windows reflect a neo-Gothic style, while the wrought-iron elements add a more modern feeling to the building .
As was fairly common in this period, the UCB building is actually a combination of the latest construction techniques (steel frames supporting vast window panes) and references to styles of the past. But, apart from the fact that bank buildings from this era are now very rare, it is the impression of homogeneity that makes this one so interesting and outstanding, which the choice of a single colour scheme tends to reinforce.
A tapestry designed especially for the new building by Pieter Vermeersch (Kortrijk, °1973) constitutes the crowning glory of this like-for-like restoration.