Egyptian authorities spotted the artefact - stolen decades before - when it was offered for sale in an exhibition in London in 2013.
A little-known culture built arrow-straight roads and canals through thick jungle to connect urban settlements where they ate sweet potatoes and drank beer.
The site of Palace of Aigai,near modern day Vergina in northern Greece,has undergone a 16-year renovation that cost more than $30 million.
Despite the skill which would have been required to make it,the roughly 1200-year-old object has no apparent purpose.
Scientists have known for some time that a giant asteroid smashed into Earth causing mass extinctions. But precisely how it happened was until now not understood.
One area shows smooth grooves in the rock thought to be where indigenous inhabitants once sharpened their arrows and spears long before Europeans arrived.
The footprints were discovered at the edge of an ancient lakebed in White Sands National Park and date back to between 21,000 and 23,000 years ago.
The cache of exceptionally intact artefacts,including hilts and scabbards,tells a story of empire and rebellion,of long-distance conquest and insurrection.
The wall was first spotted by farmers during harvesting work in the Viru Valley,some 480 kilometres north of the capital Lima.
Hartwig Fischer has stepped down after admitting the 270-year-old institution was facing a situation of the “utmost seriousness”.
Ittai Gradel,the Danish art dealer who raised the alarm,said the museum’s deputy director had “basically told me to get lost”.