Peru is demanding that Yale University return an entire collection of antiquities excavated at Machu Picchu in 1912 that it insists was deposited at Yale only as a loan.
http://www.stltoday.com/stltoday/news/stories.nsf/stlouiscitycounty/story/2E25424B3CC6C68E8625712000813AC6?OpenDocument&highlight=2%2C%22antiquities%22
Greece and Turkey also claim that U.S. museums hold artifacts looted from their soil.
http://www.bloomberg.com/apps/news?pid=10000088&sid=a_6ssJtZ2pt0&refer=culture
Ethiopia wanted obelisk returned to it from Italy. They got it back, but it is still sitting pieces.
http://www.iol.co.za/index.php?set_id=1&click_id=31&art_id=vn20060227011059174C927322