It is one of the most important and outstanding collections in the museum, due largely to the series of mural paintings it includes. Indeed, the Museu Nacional Romanesque Collection is unmatched by that of any other museum in the world. Many of the works here originally adorned rural churches in the Pyrenees and other sites in Old Catalonia, or "Catalunya Vella", as it is known; they began to be discovered and studied in the early 20th century, particularly after a Pyrenean expedition in 1907 by the Institut d'Estudis Catalans (Institute of Catalan Studies), which later published "Les pintures murals catalanes" (Catalan Mural Paintings). Years later, the news emerged that a group of foreign financiers and antiquarians had block-purchased most of these paintings to be taken to the United States of America. Although there were no laws in Spain at that time to forbid the expatriation of art, the Junta de Museus (Catalan Board of Museums) was able to successfully intervene in order to rescue, dismantle and transfer works to the Museum of Barcelona (1919–1923), then housed in the Parc de la Ciutadella, thus conserving and protecting these Romanesque works, considered a completely unique piece of art heritage and also a symbol of the birth and formation of Catalonia.