π«π· Paris
Catacombes de Paris
quirkyhistorymust-see
Moved underground starting in 1786 β central Paris cemeteries had overflowed so badly that walls were collapsing into neighbours' cellars.
A 1.5 km walk through tunnels stacked with the skeletal remains of six million people, relocated here in the late 1700s from overflowing Parisian cemeteries. It is genuinely unforgettable, slightly creepy, and the kind of thing teens love. Getting through it is 131 steps down and 112 back up with no elevator. Tickets are released seven days ahead and the timed slots vanish fast; book the second they open.