The six million skeletons hidden in tunnels under Paris' streets
Even if temperatures are heatwave-level outside, it's generally never warmer than 14 degrees inside the Catacombs, making the tunnels the perfect cool escape from warm weather.
Tickets Alert: Tours of Brompton Cemetery's catacombs
Brompton Cemetery is one of the Magnificent Seven Victorian cemeteries, designed to resemble a large open-air cathedral, featuring impressive catacombs and a central colonnade.