A palatial building rests by Rue de Bois Sauvage of Brussels, an intimate street located at the exact point where the lower historic city ends and upper bureaucratic city starts. The Palace remains like a parasite of a larger introverted structure that fortifies an entire urban block to hide the offices of the National Bank of Belgium. The architectural brief for this graduation project requests the renovation of the headquarters concerning the vacancy of office space with the greater intention of opening up the National Bank as an institution. To the light of this brief, this architectural thesis departs from the premise that in order for the Bank to open up it must get engaged in the problems of its nearby reality, the problems of the city of Brussels. The in depth analysis of the history of urban transformation of the city of Brussels led by land speculation, revealed the problems of the Central European capital cities during the second half of the 19th century, which have been unavoidably inherited by the city of the 21st century. The process of urban gentrification of the historic town, firstly by pushing out the working classes to the periphery in favour of the wealthy bourgeois and secondly exploiting land value financially erasing any hint of residential life from the old city at the heart of Brussels’ Pentagon. The result of these consecutive processes of urban transformation can be read in space through the architectural typology of Brussels and have been explained in this research by means of the alley, the shopping arcade, the corner building and the blocks of Brusselization. Understanding them not only as architectural devices but also as urban figures has helped untangling the history of urban gentrification in Brussels which constructed through time a division between the rich bureaucratic upper eastern city and the working class neighbourhoods in lower western Brussels, articulated by a touristic uninhabited historic city where the National Bank of Belgium sits. More than anywhere else, Bd Berlaimont and the building of the NBB are examples of this urban transformation that has emptied from the residential life of this area of Brussels. In a process that anticipated Brusselization, the NBB made sure to erase a mixed block where housing and retail used to make a piece of the city to turn it into a monolithic impenetrable office block. This essential aspect of the site, together with the research make a project with three fundamental intentions: - Create a public route able to establish another point of connection between upper and lower Brussels, increasing the porosity of the city and the permeability of an existing urban structure. - Reprogram the block to revert the process of Brusselization and erode its monolithic nature through the introduction of residential and retail functions. - Maximise the value of the land property which is currently owned by the NBB to launch a program of affordable housing capable of setting a starting point to revert the process of gentrification and land speculation that has historically threatened the process of urban transformation of the city. These three points become the nexus between the conclusions of the research and the design decisions that followed the P2 and P3 examinations. Therefore the final design proposal is concerned with each of these aspects, from the scale of the building mass and how it is oriented towards the city, to the scale of a service staircase that tries to create a partition situation between two different programs embedded in the block. Ultimately, the project envisions an urban transformation led by the National Bank of Belgium where the use of land property, the State of the Bank, is key to face land speculation and control housing prices. The unavoidable typology of Brussels, (impasse, arcade and corner building) builds a city within the ruin of the Palace of the National Bank of Belgium.