Els Quatre Gats is a café in Barcelona, Catalonia, Spain that famously became a popular meeting place for famous artists throughout the modernist period in Catalonia.
I only recommend walking around the Barceloneta beach at sunset, there are fewer people and in the fall and spring seasons is very nice to sit on a terrace watching the sea and entertaining yourself with the activities of the area.
Where the lights come from is the national museum of art in Catalunya. Its an impressive building with great exhibitions and a huge collection of hostoric art. In that area you will also find Mies Van Der Roes house and Caixa forum (Av. Francesc Ferrer i Guàrdia, 6-8).