Spain Palau de les Arts Reina Sofía

The Palau de les Arts Reina Sofía is an opera and cultural center in Valencia. The building was opened on 8 October 2005. The first performance took place on October 25th of the same year with the opera Fidelio by Ludwig van Beethoven. The Palau de les Arts Reina Sofía is part of the Ciudad de las Artes and de las Ciencias and was designed by the Spanish architect Santiago Calatrava. The opera house is characterized by its unusually curved construction. The narrow roof arches outwards in the form of a folded ball segment. The outer walls also describe curve-shaped lines. At the highest point, the building reaches 75 meters spread over 14 floors; Underneath the ground floor are three further floors. The house is 230 meters long and offers a total area of 40,000 m². This makes it the largest opera house in Europe.
Quote:Wikipedia

If you have accommodation nearby then walking is best, otherwise public transport is very good.