The executive capital – Brussels, Belgium, where the MEPs work for the majority of the time – is often considered to be the European Union's unofficial capital.

Immeuble Louise Weiss of the European Parliament in Strasbourg
Recently, Strasbourg has been the subject of some debate. Cecilia Malmström, a Swedish member of the European Parliament, started an online petition in which the constant travel between Brussels to Strasbourg by members of the Parliament at a cost of 200 million euros per year is criticised and a call to make Brussels the seat of the European Parliament is made.
Strasbourg also houses the Eurocorps headquarters as well as the Central Commission for Navigation on the Rhine ([1]), the European Directorate for the Quality of Medicines ([2]) and the Franco-German television channel, Arte.
France and Germany are negotiating the creation of a Eurodistrict straddling the Rhine, combining the Greater Strasbourg and the Ortenau district of Baden-Württemberg, with some common administration.
The combined population of this "European Washington, D.C." would be 860,000. The original idea of Strasbourg as "capital of Europe" came from Winston Churchill.