1The historic district of Sana’a — Yemen

At its peak, this ancient part of the Yemeni capital was a picture-perfect labyrinth of mosques, homes, and traditional bathhouses.

But much of the UNESCO World Heritage-listed site was razed by a Saudi-led airstrike in September 2015; just one incident in the ongoing conflict between the alliance of Sunni Muslim Arab states and the Iranian-aligned Houthi movement that is believed to have cost almost 100,000 lives.