The following Directorates-General (departments) are also based in the Berlaymont: Human Resources and Security (HR), European Political Strategy Centre, formerly known as Bureau of European Policy Advisers (BEPA), Communication (COMM), Brussels Office of Infrastructure and Logistics (OIB), Secretariat-General (SG) and the Legal Service (SJ).

[2] The office of the president, the Commission, and the boardroom, are on the 13th floor, together with the meeting room of the "Hebdo", as well as the restaurant La Convivialité.

The situation, which started as soon as they arrived due to the lack of large office blocks, became critical and the Commission tried to concentrate its staff in a number of rented buildings around the Robert Schuman Roundabout.

The Belgian Government, becoming aware of the problem and keen to ensure that the Commission stayed, offered to build a prestigious administration complex large enough to house the entire staff.

President Walter Hallstein was interested but cautious about making long-term commitments while the issue of where the institutions were based was still being discussed.

[4] The Belgian Government's proposal required sufficient land, which would preferably be in the Leopold Quarter (where they were already based) and near the homes of the civil servants to the south and east.

The south wing would take longer given the need to demolish more buildings including the girls' school, with the Ladies of Berlaymont unable to vacate until 1963.

The Belgian Government, realising that budgetary constraints meant it could not meet any of the deadlines, resorted to outside funding from the Office de sécurité sociale d'Outre-mer (OSSOM).

Completion was pushed back from the start of 1966 by a year due to the rail companies failing to vault the nearby railway line that prevented access to the ground floor.

The general public most associated the Commission with the Berlaymont and it was seen as a matter of pride that they occupy the entire building.

[11] Renovation of the building became the responsibility of the Belgian State when it bought the Berlaymont from OSSOM in 1985, but put off any work due to budgetary constraints.

The civil servants' trade unions put on the pressure and the issue was used as a pretext for a full renovation as the facilities had become outdated and were not able to cope with the influx of new member states.

[12] Demolition was not an option as the foundations anchored the local road and metro networks, which would be put in danger if the Berlaymont were to be knocked down.

Hence, it was decided to bring in private sector financial institutions in the form of a management and renovation company: SA Berlaymont 2000 (in which the Belgian State remained a major shareholder).

Eventually, the plans were adapted enough for the Commission not only to accept them and return to the Berlaymont but to pay the renovation costs, signing a long lease in 1997 with an option to purchase.

The December 1998 handover date was delayed five times and the bill to the Belgian State for the poor planning and disagreements amounted, by some estimates, to €824 million.

It was directly inspired by the 1958 secretariat building of UNESCO in Paris (which was designed by Marcel Breuer, Pier Luigi Nervi and Bernard Zehrfuss).

The top, 13th, floor however was supported directly by the upper beams, suspended entirely by them making the lower level free standing except for the core.

The number of lower levels (which link to the road tunnels and metro) was due to the 55 m (180 ft) height restriction around the Cinquantenaire (so as not to spoil the view)[25] It included 17 flexible conference rooms that could be used by the European Parliament and Council of Ministers.

[26] The façade was replaced with a curtain wall with mobile glass screens that adapt to weather conditions and reduce glare while still allowing light in.