In the 1870s and 1880s, Nobel built up a network of factories all over Europe to manufacture explosives. In 1894, he bought an ironworks at Bofors in Sweden that became the nucleus of the well-known Bofors arms factory. Although he lived in Paris, Nobel travelled widely. He continued to work in his laboratory, inventing a number of synthetic materials and by the time of his death he had registered 355 patents.