The Banque Générale du Luxembourg (BGL), established in 1919, is one of Luxembourg’s iconic financial institutions. Drawing on the bank’s private archives, this article explores the many architectural changes made to the BGL headquarters over the years, ranging from extensions and renovations to new building projects. Throughout the bank’s history – and especially from its establishment until the late 1980s –, the buildings that housed its head office in the centre of Luxembourg City went through multiple transformations. The architectural history of the headquarters is not only intricately linked with the history of the bank and the image it sought to portray; it is also a key chapter in the growth of the Luxembourg financial centre and reflects the wider urban development of Luxembourg City. While the first head office was still characterised by classical architectural features, its transformation towards a more functional, vertical aesthetic in the 1960s had a lasting impact on the city centre landscape: the BGL was one of the first financial institutions to engage in a radical overhaul of its headquarters on boulevard Royal.