Although European civil servants have been based in Brussels for many decades it was only in 1997 (Treaty of Amsterdam) that it was officially stated that the Commission should have its seat in Brussels.
In short, most Commission staff work in Brussels, although more than 2,000 are based in Luxembourg and other locations in Europe. There are Commission representative offices in all 27 countries of the European Union. There are also over 120 delegations located around the globe - from Peru to Papua New Guinea, dealing with such matters as trade, development and humanitarian aid.
The buildings of the European Commission are dispersed allover Europe: