On stamp # 21/10 of the Album Catalunya, we see a boulevard named (on the stamp)"Avinguda 14 d'Abril" (14th April Ave.) and a "spiky house" right on the middle.
The street is what today we call "Avinguda Diagonal" (Diagonal Ave.). A very proper name, as it cuts diagonally the "new town" street grill. Built after demolition of city walls in 1854.
But it has had many names since its birth (on paper)in 1867:
.- 1867/1874: Gran Via Diagonal
.- 1874/1922: Avenida de Argüelles (Spanish, long time ago forgotten, politician)
.- 1922/1924: Avinguda de la Nacionalitat Catalana (Catalan Nationhood)
.- 1924/1931: Av. Alfonso XIII (king of Spain 1886/1931)
.- 1931/1939: Av. 14 d'abril (date of proclamation of the Spanish and Catalan republics)
.- 1939: Gran Via Diagonal
.- 1939/1979: Av. Generalisimo Franco (Spanish dictator, 1939/1975)
.- 1979 to day: Avinguda Diagonal
The house in the middle is Terrades House (known as "The house of the spikes" by Catalans) which was built in 1905 by Josep Puig I Cadafalch. It's a Modernist building.

On the back, you can see the Sagrada Familia Temple Belfries.