Entrance to the Natural History Museum in Balboa Park. It was founded in 1874 as the San Diego Society of Natural History and is the third oldest scientific institution west of the Mississippi and the oldest in Southern California. In 1917, the Society purchased a vacant Balboa Park building from the 1915 Panama-California Exposition and created the San Diego Natural History Museum. It resided in 3 different buildings until the permanent one was built in 1933.