Museum that collect and display work of art are known as art galleries. A museum or gallery is a building or institution which exhibits work of art or other objects of scientific, artistic, or historical importance and makes them available for public viewing. The exhibition may be permanent or temporary. The first public museums in the world opened in Europe during the 18th century. Museums are usually open to the general public, sometimes charging an admission fee. Some museums are publicly funded and have free entrance, either permanently or on special days. There are many types of museums, categories include, archaeology museums, art museums, history museums, maritime museums, military and war museums, mobile museums, natural history museums, open air museums, science museums, specialized museums, virtual museums, zoological parks and botanic gardens.