ABOARD THE MV CASANOVA — William Shakespeare wrote a dozen plays about Renaissance Italy, but never planted a buskin there. Yet the Bard looms large, both culturally and commercially, in Venice and Padua, Verona and Mantua, indeed most everywhere in the valley of the Po.

Going down Venice's Grand Canal, Charles Dickens imagined he saw "old Shylock passing to and fro upon a bridge and a form I seemed to know as Desdemona leaning out a latticed window to pluck a flower. I thought that Shakespeare's spirit was abroad upon the water somewhere, stealing throughout the city."

We had the same eerie Elizabethan feeling when we boarded the MV Casanova, a slow boat to Shakespeare's Italy. Just before sailing, we strolled down the fondamenta, the embankment, and saw a girl in a Padua University T-shirt studying a poster for an upcoming Shakespeare festival. She offered to show us Othello's house along the Grand Canal, his tomb in the church of San Giobbe and the very spot near the Rialto bridge where Shylock had his pawnshop and demanded his pound of flesh.

The two Moors striking the hour on the bell tower in Piazza San Marco, she assured us, were "Othello's cugini," his cousins. If we had time, she could also show us Desdemona's digs. Probably Portia's pad, too, but the 6 p.m. departure time summoned us to other venues where the Bard's characters lived on.

Now in its third season on the Po River, the five-star Casanova headed up the lagoon to the flutter of pigeons and the angelus chimes of 107 churches, past that bizarre blend of Gothic, baroque and Byzantine palazzos and basilicas outlined against a baby blue Canaletto sky.

"Opium couldn't build such a place," Charles Dickens once mused about Venice. The city is even more dreamlike when viewed from the deck of a boat as sunset guilds the Doge's palace and the domes of the Salute, San Giorgio Maggiore — Palladio's masterpiece and the clustered oriental spires of fabulous St. Mark's.

"It is a sight that I never tire of," remarked Capt. Joachim Schramm as he detoured the 335-foot-long riverboat with gleaming white with red trim into the Canale Bianco, the White Canal. Rising in the Alps, Italy's longest river curls and twists and piles up shoals for 425 miles in an unpredictable, unruly torrent of alternating dangerous floods and incorrigible low water.

The unpotable Po was proving uncooperative again. Last evening a rival riverboat got hung up on a sandbar, so the captain ventured up this pleasant, little-used canal, lined with fields of rice and asparagus and ancient farm buildings with red tile roofs. Off in the distance, like cones of gelato, Italian ice cream, loomed the snow-tipped Alps.

Along the banks, poppies, honeysuckle, wild irises and mushrooms glowed like fire opals among the reeds. Joggers and bikers kept pace with our 5-knot speed, and whole families alighted from cars and mo-peds to wave as we passed through century-old moss-covered locks.

Being on a German-registered boat, boasting all the amenities and then some, we waved back with foamy glasses of free pilsner from a keg brought up on deck for passengers preferring something more bracing than morning bouillon.

To our astonishment, the pilot house suddenly almost disappeared from sight as we passed under a low bridge, and a deck hand shouted "heads down" in German and English. The captain was left with only a tiny slit of window to peer through, offering less visibility than a submarine commander leaning into his periscope.

The pilot house kept retracting into its own elevator shaft, like a turtle going into its shell, as we slid under a series of bridges, one so low a sailor chinned himself on the span as we waited to enter another lock.

Around a bend, two naked nymphs sunbathing at the water's edge were startled to see a three-deck riverboat, bigger than a soccer field, glide by. They ran up the bank hugging their clothing.

The Casanova caught up with the mainstream Po near Mantua, and the great plain of Lombardy spread out in emerald fertile fields, patches of pine and poplar forest and remarkably beautiful marshes that lie along northern Europe's migratory bird routes. More than 150 bird species have been logged here.

Cuckoos called to us along the banks; cormorants, glebes and egrets preened in the tall reeds; sea swallows skimmed our wake and a pair of gorgeous purple herons spread their enormous wings for a flyby.

Industrial pollution from chemical and power plants and excessive spraying of rice fields with herbicides have rendered the Po unfit to swim in or drink. But you can drink in some of the same serene scenery that lured Monet, Manet, Whistler and Winston Churchill here with their paint boxes.

At the tiny town of Polesella, a spectacular double rainbow arched over the boat just as Gustav Ribbi, our Swiss pianist, arrived on deck. He immediately launched into "Somewhere Over the Rainbow" on the electronic keyboard.

One morning along a lovely stretch of river, an Italian Tom Sawyer, barefoot and sun-bronzed, reeled in a dark, ugly fish almost as big as himself and tied it to his bicycle. "Not to eat," warned Dr. Klaus Ziergiebel, the Casanova's surgeon who thought the catch was a carp, a species which somehow manages to survive in these polluted waters.

Because the Po, like the Mississippi, keeps eating its banks and changing course, few towns are located right on the river. From our nearest docking place, Mantua was a 15-minute tour bus ride, Verona and Cremona were 45 minutes away, Bologna and Ferrara an hour, and Padua was reached in less than an hour by a tender and bus. All were worth the visit.

Ask not in Verona "Romeo, Romeo, wherefore art thou Romeo?" He is everywhere. So is his nymphet bride, Juliet, "not yet 14," as Shakespeare tells us. Via Cappello, alias Capulet, leads to the 14th-century Casa di Giulietta, where Juliet's lover, Romeo Montecchi, renamed Montague by Shakespeare, stalked her from beneath the balcony. British novelist Arnold Bennett, viewing the alleged house as tourists still do in droves, thought the balcony "too high for love unless Juliet was a trapeze artist accustomed to hanging by her toes."

In the courtyard there is a bronze statue of Juliet, much polished over the centuries by the embrace of lovers. Via Arche Scaligeri leads to what romantics insist is Romeo's house, decked with a smaller balcony, presumably for practice. Locals also show you Juliet's tomb in the crypt of the church of San Francesco Corso, where Lord Byron scoffed at this sarcophagus large enough to bury a regiment, but took away some souvenir pebbles for his daughter.

Verona offers a summer season of Shakespeare at the Teatro Romano, and two hotels with cozy bars pay homage to the Bard, the Giulietta Romeo and the De Capuleti.

In Mantua, just off the lovely Renaissance square dominated by the 500-room Palazzo Ducale, guides point out the apothecary shop where Romeo, thinking Juliet was dead, purchased his suicide poison.

Encircled by three lakes and with four interlocking squares leading to the barrel vaulted basilica of Sant'Andrea, the town looks like the sound stage for one of Franco Zeffirelli's lavish filmings of a Shakespeare play.

Virgil was born in Mantua, which is the setting for Verdi's opera "Rigoletto." The best restaurants still feature a local delicacy that ages ago was a meal fit for a duke when the ruling Gonzaga family built their palaces: stufato d'asino, donkey stew. We passed it up and tried ravioli stuffed with pumpkin, another Mantuan favorite.

Shakespeare called Padua "the nursery of the arts," justly famous for its university where Galileo taught physics and William Harvey studied anatomy. In "The Taming of the Shrew," Petruchio comes "to wed it wealthily in Padua" by taming the fiery Kate and claiming her dowry. On the university campus there is a statue of Elena Piscopia, who would not be tamed by the sexist rules of her day and in 1678 became the first woman anywhere to win a college degree.

Thousands of pilgrims descend on Padua every day to visit the tomb of St. Anthony in the huge basilica overlooking one of Europe's largest squares and to view the Giotto frescoes in the Chapel of the Scrovegni.

Back on board, movies available on our cabin TV augmented the daily tours to Shakespeare's Italy: "Romeo and Juliet," "Much Ado About Nothing," Zeffirelli's "The Taming of the Shrew," with Burton and Taylor, and Cole Porter's marvelous musical "Kiss Me Kate."

Seen from shore, the bargelike Casanova lacks the Gothic grace of the Mississippi steamboats with their churning paddle wheels, crenelated smoke stacks and forward landing stages. But the Italian Renaissance interior decor, offset by drapes and lounge furniture in the gay carnival colors of Venice, evoked the grandeur of the Doge's golden barge. All cabins, accommodating a capacity 96 passengers, are outside. Our comfortable portside cabin, almost at water level, featured a large color print of the Rialto Bridge by Pierre Mortier.

Near the main staircase hangs a sensuous portrait of that adventurous Venetian rogue, Giacomo Casanova, the legendary lover of enduring virility who debated Voltaire, argued philosophy with Frederick the Great, was denounced as a spy by the Inquisition, escaped from the Doge's prison through a hole in the roof, seduced the six daughters of the mayor of Geneva, invented the kiss-and-tell autobiography and, for none of the above reasons, gave his name to our boat.

"He just seemed like a fun guy," laughed hotel manager Marco Corves who oversaw the parade of gourmet meals in the charming, tall windowed dining room.

Zounds and a hey nonny, nonny, as the Bard might exclaim, the whole seven-day voyage on this Peter Deilmann Cruise verily was a merry Elizabethan romp. Enter hautboys with torches, bearing baked Alaska for the captain's gala farewell dinner.

Seven-day Po River cruises on MV Casanova range from $1,500 to $2,395 per person, exclusive of airfare, depending on season and cabin accommodation. Port charges of $70 are extra.

If you go . . .

For reservations, contact Peter Deilmann Cruises at (800) 348-8287, visit www.deilmann-cruises.com, e-mail: pdcmaildeilmann@cruises.com, or write Peter Deilmann Cruises, 1800 Diagonal Road, Suite 170, Alexandria, VA 22314.