did-you-kno:

Nikola Tesla once paid an overdue
hotel bill with a ‘working model’ of his
‘death beam’. He warned the staff never
to open it, describing it as a war-ending
particle weapon that could stop invading
armies and make warfare pointless.
After his death in 1943, someone finally
pried the box open and found nothing
but a bunch of harmless old
electrical components. Source Source 2