Barcelona
Gaudi's eclectic architecture is sprinkled around this coastal city, which has been long hailed as a European cultural capital. Head to the Eixample district, where you'll find some of the most breathtaking Modernist mansions such as Casa Battló, La Pedrera and Casa Ametller (by Puig i Cadafalch, a contemporary of Gaudí).
Take a walk around and you'll find public art on every corner, outdoor exhibitions brimming with life and contemporary art by world-renowned artists like Banksy and teamLab in the city's creative spaces.