After World War II, the "Bricks for Warsaw" campaign was initiated and large prefabricated housing projects were erected in Warsaw to address the major housing shortage. Plattenbau apartment blocks were a solution to avoid Warsaw's former density problem and to create more green spaces. Some of the buildings from the 19th century that have survived in a reasonably reconstructible form were nonetheless demolished in the 1950s and 1960s, like the Kronenberg Palace. The Śródmieście (central) region's urban system was completely reshaped; former cobblestone streets were asphalted and significantly widened for traffic use. Many notable streets such as Gęsia, Nalewki and Wielka disappeared as a result of these changes and some were split in half due to the construction of Plac Defilad (Parade Square), one of the largest of its kind in Europe.