There is an old Venetian legend which says ...
If two lovers…read more...
kiss ...
in a gondola ...
under the Bridge of Sighs ...
at sunset ...
when the bells of the Campanile toll ...
they will love each other ...
forever ...
The legend is true.
Smooching while gently gliding on Rio di Palazzo under Ponte dei Sospiri (with a furtive glance from your gondoliero) is the most "romantic" way to experience this very popular tourist attraction near Canal Grande behind Palazzo Ducale.
The other two ways to enjoy Venice photo spot #4 (or #2063 depending on which way your walking) aren't nearly as amorous.
The "easiest" experience is to join the throngs of tourists crowded onto the Ponte della Paglia stone bridge (built in 1847 near Piazza San Marco) to get the same pic as every other single person that has visited Venice since 1848. It's a local custom (which may be an actual law) that you MUST take a picture of Ponte dei Sopiri from this view point.
The most "educational" way to visit the Bridge of Sighs is the old-fashioned way ... like prisoners (such as the infamous Casanova) ... did since 1603 when being led from the interrogation rooms of Palazzo Ducale (Doge's Palace) to the Prigioni Nuove (New Prison). Take the self-guided tour of the palace to explore within the covered bridge.
Inside, you can peek from the small windows carved into the ornamental Istrian limestone while learning more about why the bridge earned it's title as the "last view of Venice" ... causing prisoners to *sigh* on their way to the famously-cold, wet, and windowless jail.
Why the sigh?
Oh, it's this bridge.
If you're already at Ponte dei Sospiri, why not take some (obligatory) pics? Whether they are the most romantic, easiest, or educational is forever entirely up to you.