The size and importance the urban regulation of "Downtown Zagreb" (largely the work of "Milan Lenuzzio", 1860–1880) was revolutionary. Between Zagreb's longest street – Ilica, and the new railway the new geometrical city was built with large public and social buildings like the neo-Renaissance building of the "Croatian Academy of Science and Art" (HAZU, F. Scmidt, 1884), the neo-Baroque "Croatian National Theater" (HNK, H. Helmer and F. Fellner, 1895), and to that date very modern "Art Pavilion" (1898) with montage construction of steel and glass – Croatia's "Crystal Palace", and finally the masterpiece of Art Nouveau – "The National Library" (Lubinski, finished in 1912). This urban plan is bounded with a series of parks and parkways decorated with numerous fountains, sculptures, avenues and gardens (known as "Green Horseshoe") making Zagreb one of the first cities build according to new European art theory of "city as a work of art".