During the fall of Baghdad in 2003, thousands of artifacts were taken from the Iraqi capital’s National Museum, whose holdings documented the rise of civilization in ancient Mesopotamia. Scholars called the losses a tragedy for all of humanity.

Since the looting, about 5,000 artifacts have been recovered and returned to Iraq, including the antiquities shown here that were seized by Syrian authorities after they were smuggled across the border. About 600 of the artifacts that had been returned went missing once more – and were found again just this month, misplaced among kitchen supplies at the Iraqi prime minister’s office.

Experts believe more than 15,000 artifacts remain at large.

Check out six more historical and archaeological treasures lost to wars and conflict, from the invasion of Iraq to a 17th century attack on the Parthenon. Some treasures have been restored or replicated; others are gone forever.