The Naturalis Biodiversity Center is a natural history museum and biodiversity research center in the city of Leiden , the netherlands.

The museum houses one of the largest natural history collections in the world which has about 42 million specimens including: insects, molluscs, invertebrates, vertebrates (birds, fish, reptiles and amphibians, mammals), fossils, rocks and minerals, plants vascular, moss, lichen, fern, fungus, gall algae and wood specimens.

The museum also houses over 140,000 books, 14,000 scientific journals, 57,000 prints and drawings, 13,000 maps, 91,500 microfiche, 310,000 photographs and slides.

Among them are manuscripts and field research notes from many past explorers and naturalists.