Sienna Miller and Heath Ledger in "Casanova"

There are two ways to look at Giacomo Casanova, the 18th century Venetian whose legend retains a hold on our imagination two centuries after his death. There is the real Casanova, whose eleven volumes of memoirs seem barely sufficient to contain his exploits as a diplomat, a politician, and a spy; a musician and a writer; a Freemason and a cleric; and a swordsman, in both senses of the word. That his biography isn’t entirely trustworthy only adds to his allure.

Or you can regard him for the trait with which his name has become synonymous, as history’s greatest lover, the man whom no woman could resist. Plenty of softcore fantasies have been spun about the latter, but aside from Fellini’s 1976 film with Donald Sutherland as an aging sexual obsessive given to bouts of mechanical fornication, few have shown much interest in the real man.

Lasse Hallström’s Casanova is so lacking in bawdiness that it barely earns its R rating. But after seeing it, you still won’t know Giac. Concentrating on a fictional incident in the life of Casanova at the age of 28, it uses a dash of historical fact (Casanova’s run-in with the Spanish Inquisition, which sought to execute him as a warning against immorality) as the basis for a romantic farce. Heavy on pretty costumes and prettier actors, it aspires to be a popular updating a la Tom Jones, Richard Lester’s Three Musketeers films, or Shakespeare in Love, but it is no more grounded than the hot air balloon that figures prominently in the story.

Without detailing the multiple impersonations and mistakes of identity that move the film along, suffice to say that Casanova (Heath Ledger, more prominently on display this week in Brokeback Mountain), compelled to take a wife, finds one suitable to him in the person of Francesca Bruni (Sienna Miller), a protofeminist who wields a mean sabre and who writes (under a nom du plume) subversive tracts on gender freedom. Because the movie would only be thirty minutes long if they immediately recognized each other as soul mates, much persiflage and chicanery ensues prior to an ending that at least addresses the need to redress the story’s main historical inaccuracy.

The nicely dressed supporting cast includes Jeremy Irons (camping it up in a ridiculous wig as the Papal Inquisitor on the trail of both of our heroic heretics), Lena Olin (aka Mrs. Hallström) as Francesca’s mother, and Oliver Platt as a Genoan lard merchant (and the subject of a lot of fat jokes unbecoming to an actor of his talents, not to mention some slapstick torture scenes that are in spectacularly poor taste at a time when our government is trying to persuade us that it has the right to torture real people).

Call me a dirty old man, but a little genuine smut would have been welcome here. Instead, all we get is a few scenes of Casanova cavorting in one of those convents that exists only in European soft porn films, and a dinner table scene swiped from Shampoo. Instead, this is a Casanova that you could take your mom to see.