This nearly 200-year-old bar— reputedly the oldest in Barcelona, is an absynthe bar. Was one of the locations from Vicky Christina Barcelona's film.
The Marsella is one of those places that Hemingway supposedly loved to frequent (Hemingway being to bars in Spain what George Washington is to inns in New England).
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).
It is a cultural center that organizes and produces exhibitions, debates, festivals and concerts, programmes film cycles, courses and lectures, and encourages creation using new technologies and languages. You can also find inside a nice cafe, a bookshop and a library, I love to go there on sundays, to discover new artists or just have some tea and look at some art books.