One of the first films in which Claudia Cardinale, who was born in Tunisia and whose first language was French, dubbed herself in Italian.
Luchino Visconti wanted Tab Hunter for the role of Andrew Dawson, but the producers felt his name didn't have enough clout at the box office and, strangely enough, chose Michael Craig, whose name meant decidedly less, instead.
Luchino Visconti himself described the film as "a detective story in which everything is clear at the beginning and obscure at the end."
Volterra is a walled mountaintop town in the Tuscany region of Italy. Its history dates from before the 8th century BC and it has substantial structures from the Etruscan, Roman, and Medieval periods.
"...stelle dell Orsa" means "the constellation of the Bear", which Heraclitus called an "immortal witness" of human affairs because it never disappears below the horizon.