with only a sea of rubble remaining. The immense destruction prompted a temporary transfer of the new government and its officials to Łódź, which became the transitional seat of power. Nevertheless, Warsaw officially resumed its role as the capital of Poland and the country's centre of political and economic life. 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-styled apartment buildings were seen as 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. On 14 April 1966, a millennial military parade was held in Warsaw to commemorate the 1000th anniversary of Poland's statehood. It involved a number of troops in the parade from different eras of Poland's history. Much of the central district was also designated for future skyscrapers. The 237-metre Palace of Culture and Science resembling New York's Empire State Building was built as a gift from the Soviet Union. Warsaw's urban landscape is one of modern and contemporary architecture. Despite wartime destruction and post-war remodelling, many of the historic streets, buildings, and churches were restored to their original form. John Paul II's visits to his native country in 1979 and 1983 brought support to the budding "Solidarity" movement and encouraged the growing anti-communist fervor there. In 1979, less than a year after becoming pope, John Paul celebrated Mass in Victory Square in Warsaw and ended his sermon with a call to "renew the face" of Poland. These words were meaningful for Varsovians and Poles who understood them as the incentive for liberal-democratic reforms. 1989–present In 1995, the Warsaw Metro opened with a single line. A second line was opened in March 2015. Warsaw is experiencing the largest economic boom of its history. The opening fixture of UEFA Euro 2012 took place in Warsaw and the city also