 He also recognized important creole savants in Mexico, including José Antonio de Alzate y Ramírez, who died in 1799, just before Humboldt's visit; Miguel Velásquez de León; and Antonio de León y Gama.Humboldt spent time at the Valenciana silver mine in Guanajuato, central New Spain, at the time the most important in the Spanish empire.The bicentennial of his visit in Guanajuato was celebrated with a conference at the University of Guanajuato, with Mexican academics highlighting various aspects of his impact on the city.