The EU unveiled its futuristic new 321-million-euro headquarters on Wednesday, saying it symbolised 'joy' at a time of rising populist anger against Brussels that helped lead to Brexit.

A glass lantern-shaped structure inside a cube made of recycled window frames sourced from across the 28-nation bloc, the Europa building has been dubbed the "Space Egg" because of its otherwordly appearance.

At its heart is a huge room decked out in psychedelic rainbow carpets and ceiling tiles where European Union leaders will hold their summit meetings on the multiple crises that beset the bloc.