'The Memory Of Mankind'

If you add up the attendance for every major-league baseball, basketball, football and hockey game this year, the combined total will come to about 140 million people. That's a big number, but it's barely a fraction of the number of people who will visit American museums this year.Museums are big business, attracting billions of tourist dollars, advancing science, and educating and amusing more than 850 million people annually.

Read more at NPR's A History Of Museums, 'The Memory Of Mankind'

Schoolchildren visiting New York's Junior Museum of the Metropolitan Museum of Art watch slides of artists at work in the 1950s. Carsten/Three Lions/Getty Image