an intellectual centre of both Estonia and the Baltic countries for several centuries. Scholars hailing from Tartu include the pioneer of embryology Karl Ernst von Baer, a pioneer of animal behaviour studies Jakob von Uexküll, and a cultural theorist and semiotician Juri Lotman. Johann Friedrich von Eschscholtz, a Baltic German physician, naturalist, and entomologist, was born in Tartu. He was one of the earliest scientific explorers of the Pacific region, making significant collections of flora and fauna in Alaska, California, and Hawaii. Nobel Chemistry Prize laureate Wilhelm Ostwald studied and worked in Tartu. The Tartu School is one of the leading scientific schools in semiotics. Main sights The architecture and city planning of historical Tartu mainly go back to the pre-independence period, with Germans forming the upper and middle classes of society, and therefore contributing many architects, professors and local politicians. Most notable are the old Lutheran St. John's Church (, ), the 18th-century town hall, the university building, ruins of the 13th-century cathedral, the botanical gardens, the main shopping street, many buildings around the town hall square and Barclay Square. The historical slum area called Supilinn (Soup Town) is located on the bank of river Emajõgi, near the town centre and is regarded as one of the few surviving "poor" neighbourhoods of 19th-century Europe. At the moment Supilinn is being rapidly renovated, undergoing a slow transformation from the historic slum into a prestigious high-class neighborhood. The active community embodied by the Supilinn Society is committed to preserving the heritage. The Second World War destroyed large parts of the city centre and during the Soviet occupation, many new buildings were erected – notably the new Vanemuine Theater. The effects of the war are still witnessed by the relative abundance of parks and greenery in the historic centre. Typical Soviet-style neighbourhoods of blocks of high-rise flats were built between World War II and the restoration of Estonian independence in 1991, the largest such district being Annelinn. Presently, Tartu is also known for several modern buildings of the "steel, concrete and glass" variation, but has managed to retain a mix of old and new buildings in the centre of town. Notable examples include the Tigutorn Tower and the Emajõe Centre, both built during the current period of independence; Tartu's tallest and second tallest towers, respectively. Tartu's large student population means that it has a comparatively thriving nightlife, with many nightclubs, bars, and