The Charlemagne building is a high-rise in the European Quarter of Brussels, Belgium, which houses the Directorate-General for Economic and Financial Affairs, the Directorate-General for Trade, and since 2015, the Internal Audit Service of the Commission.

It is located at 170, rue de la Loi/Wetstraat, in the City of Brussels, one of the 19 municipalities forming the Brussels-Capital Region.

The renovation was completed in 1998 by the German-American architect Helmut Jahn, replacing the largely concrete exterior with a glass one.

After the restoration, it was occupied by the Commission, further grouping the Union's offices around the Robert Schuman Roundabout.

[1] The building was briefly considered as the future headquarters of the European External Action Service, established in 2010, but was discounted on image grounds; as it houses RELEX, people would see the EEAS as a RELEX-plus rather than a unique body outside of the Commission.