Although parts of Paris' Notre Dame Cathedral now lie in ruins, people can still experience what most of its nooks and crannies looked like in remarkable detail -- thanks to an American art historian.
Andrew Tallon , a professor of art at Vassar College, used lasers to painstakingly scan the cathedral in 2015, giving us a nearly perfect digital replica of the Gothic structure.
And his work could help architects and engineers rebuild it after Monday's fire.
Tallon studied Gothic architecture and sought to understand how medieval builders erected some of Europe's great cathedrals.
So he created a spatial map of Notre Dame using more than a billion laser-measured points.
The Notre Dame Cathedral has been repeatedly modified over almost seven centuries, making the architectural history of the building difficult to follow.
The data can show "how the building is constructed ... and you can see every corner, every detail digitally," Krusche added. »