This cross is located in one of the parks inside Sant Pau Hospital.
Remember you can admire Catalan art nouveau buildings like the one in the background if you visit the modernista complex not far away from Sagrada Familia.
There are previous posts dealing with Sant Pau or San Pablo in Barcelona Photoblog so I recommend you browse my site for more.
You will find out about the history behind the buildings or the works of the architect, Domenech i Montaner. As for example: Pillars of Catalan Art Nouveau in Palau de la Musica Catalana.