Renovated by Gaudi in the first decade of the twentieth century, this is something that Gaudi actually finished! Not only did he add his colourful Modernista touch to the facade, he also did the interior too.
Pre-book your entry and skip the line when you arrive: Casa Batllo Skip-the-Line Entry and Audio Guide
(There are a better angles from which to take photos of this building, but at least this way you'll recognise it as you walk past!)
The Illa de la Discordia is the 'Block of Discord' (Manzana de la Discordia in Spanish), a trio of modernist buildings designed by Catalonia's top modernist architects.
The Illa de la Discordia is found on the Passeig de Gracia on the left-hand side (when walking up from Las Ramblas.