German specialists. The most valuable part of the complex is NGL-Betrieb, where the nitroglycerin plant stands. The individual buildings are still preserved and connected by a near- long network of overground and underground tunnels. In 2009–2011, a project was launched to revive the area, called Open-air museum of industrial architecture with an underground tourist route and the museum of Armaments Works DAG Fabrik Bromberg. The outcome of the programme was the creation of the Exploseum, an open-air museum of industrial architecture combined with a museum of 20th century technology. Museum patron The patron of the museum lived during the interwar period in Bydgoszcz and Gościeradz, where he was buried at the parish cemetery. At the artist's death, his wife Franciszek Wyczółkowska, according to his will, handed over the artistic works legacy to the Museum of Bydgoszcz on 8 April 1937: 425 paintings, graphics, drawings, personal mementoes and studio paraphernalia. On the 94th anniversary of Leon Wyczółkowski's birth (11 April 1946), the District Museum in Bydgoszcz officially adopted the artist as its patron. Buildings in Bydgoszcz The museum collections and branches are located in the following places in the city: Museum collections Archeology department Location: White granary The section gathers objects of Bydgoszcz and its region dating from the Stone, Bronze and Iron Ages, Roman and Medieval Ages. The most interesting monuments are exhibits from the Stone Age, such as: bone blades, hoes made of reindeer horn, harpoon heads, clay funnel cups and a fragment of a dugout canoe from 2000 BC. Among the early medieval items, several thousand come from Slavic strongholds of Bydgoszcz and surroundings (old town, ancient strongholds, Nakło nad Notecią, Więcbork). One can notice a fragment excavated in 2007 of the city burgwall from the 11th century, long, wide and thick: it is a unique piece in such a scale in Pomerelia or Kujavia and one of the best preserved. Ethnography department Location: White granary The department, established in 1986, displays collections of folk culture and art, mainly from ethnocultural regions of Pałuki, Kujavia, Krajna, Tuchola Forest, Kashubia and Kociewie. There are around 3000 items registered, mainly craft exhibits (blacksmithing, pottery, carpentry, basket weaving and plaiting). Graphics department Location: Leon Wyczółkowski's house The section was created in 1982. It contains approximately 13000 exhibits in several collections: old and contemporary Polish graphics, foreign graphics, bookplates, applied graphics, drawings and monotypings. The largest section is the collection of Polish