The second half of the 20th century also saw, under the communist regime, the construction of blocks of flats (panelház), as in other Eastern European countries. In the 21st century, Budapest faces new challenges in its architecture. The pressure towards the high-rise buildings is unequivocal among today's world cities, but preserving Budapest's unique cityscape and its very diverse architecture, along with green areas, is force Budapest to balance between them. The Contemporary architecture has wide margin in the city. Public spaces attract heavy investment by business and government also, so that the city has gained entirely new (or renovated and redesigned) squares, parks and monuments, for example the city central Kossuth Lajos square, Deák Ferenc square and Liberty Square. Budapest's urban landscape is one of the modern and contemporary architecture. Numerous landmarks are created in the last decade in Budapest, like the National Theatre, Palace of Arts, Rákóczi Bridge, Megyeri Bridge, Budapest Airport Sky Court among others, and millions of square meters of new office buildings and apartments. But there are still large opportunities in real estate development in the city.