VENICE — Henry James, in “The Wings of the Dove,” called Venice’s Piazza San Marco “the drawing-room of Europe.” But currently, the attention is less at James’s “splendid square” than at the mouth of the lagoon. The 11th Venice Biennale of Architecture is currently underway in the Arsenale, a former maritime structure, and the nearby Giardini, a large waterfront park.

With its history of international trade and shipbuilding, Venice proves a munificent host to this gathering of architects from 56 countries. Participants and guests fall under the spell of the narrow pedestrian alleys, arched bridges, and vast campos anchored by churches that serve as city squares. Adding to this architectural feast — which includes robust additions and renovations by the city’s own 20th-century modernist, Carlo Scarpa — Venice has just opened (without fanfare) its new bridge by Santiago Calatrava. The fourth over the Grand Canal, it joins the Santa Lucia train station with the Piazzale Roma bus station. Like Mr. Scarpa, Mr. Calatrava has gone for context rather than exhibitionist architecture by designing a sleek marble arc of a bridge with translucent glass treads. It is supported by a dramatic Venetian-red truss one local friend aptly described as a giant fish bone.

In selecting the Biennale’s theme, “Out There: Architecture Beyond Building,” director Aaron Betsky — who heads the Cincinnati Art Museum — encouraged an exploration of “pure experiments in form, structure, and space … in temporary or enigmatic structures [or] through actions that make space our own.” The result was an eclectic quality of experimentation, often bordering on utopian visions enhanced by computerized information.

As an inspired addition, Mr. Betsky invited landscape architect Kathryn Gustafson to create the Biennale’s first garden design. On the grounds of a former 13th-century Benedictine convent, lately covered in a thick bramble of a forest, Ms. Gustafson’s team hacked away to create “Towards Paradise,” a tripartite garden installation that guided visitors through three stages of self-knowledge. “Memory” was symbolized by a warehouse where Latin names of extinct or endangered flora and fauna were listed on the walls. After walking through, the visitor emerges into a sumptuous kitchen garden for “Nourishment,” with rows of vegetables and flowers and a pergola draped in grapevines. Finally, for “Enlightenment,” Ms. Gustafson created fluid grass-covered landforms with an immense cloud-like spinnaker held aloft by white helium balloons.

In the Giardini, the national exhibitions were housed in permanent pavilions, mostly gems designed by major 20th-century architects such as Alvar Aalto (Finland) and Josef Hoffman (Austria) for previous biennales. The American pavilion, designed in 1930 by Delano & Aldrich in a Jeffersonian neoclassical mode, featured 16 new practitioners seeking “new forms of sociability and activism.”

Outstanding among these was the Panhandle Bandshell, designed by San Francisco firm Rebar out of recycled materials. The traditional form was fabricated from 65 automobile hoods over recycled structural steel capped by hundreds of computer circuit boards. The luminous back wall consisted of 3,000 16-ounce plastic water bottles, with and without tops, stuck together with silicon. Performances were scheduled for the temporary structure via a Web site. The band shell is now up for sale or lease.

At the Japanese pavilion, the theme was plants and architecture in equal parts based on the architect Junya Ishigami’s idea of making nature indistinguishable from physical structure. The entire interior walls were covered with his delicate and fanciful drawings of trees and plants as architecture while outside he constructed four vertical greenhouses planted according to ikebana principles from top to bottom with flowering vines climbing a series of poles.

Two different exhibitions featured walls of refrigerators as stand-ins for enclosed spaces. In the Czech and Slovak pavilion, the refrigerators exhibited food contents according to the relationship between “social, economic, and urban context” and the favorite foods and culinary recipes of friends and strangers studied by the organizers. In the experimental architecture section, the Berlin firm Topotek 1 treated refrigerators like individual gardens, or “a glimpse into an enchanting world.” Many of these displayed faceted jewels set in coordinated color fields.

A video display at the entrance of the Arsenale showed 100 film clips of iconic architecture. These suggested the visionary aspects of cinema, such as the emerald chamber of “The Wizard of Oz.” Inside the Arsenale’s cavernous galleries, works by the heavy hitters in architecture were displayed. Frank Gehry was represented by the scaffold of a wooden tower rendered with cracked clay by local craftsmen. Zaha Hadid’s “Lotus” room was a streamlined though amorphous structure that is both architecture and furniture for specific uses.

To celebrate the 500th anniversary of Andrea Palladio’s birth, Ms. Hadid and Patrik Schumacher created a dialogue between their architecture and Palladio’s Euclidean symmetry at the Villa Foscari (“La Malcontenta”) which is 20 minutes from Venice by car. Their installation of swirling open fiberglass and polyurethane sculptures of perfect proportions leaves an indelible image.

Venice and Italy itself were prominent subjects of the exhibition this year. Diller Scofidio + Renfro spoofed cultural tourism by showing simultaneous films of alternate Venices — canals, gondolas, and arches at perpetual sunset in Las Vegas and Macau. And in a more serious vein, the Milanese firm, Studio Albori, demonstrated plans to build a housing development within the incomplete structure of a train station in Milan originally designed by Aldo Rossi and Gianni Braghieri.

Coming up the Grand Canal on a vaporetto at night is like attending a continual party in a magical setting, with rose-tinted lantern lights posted along the canal and outside the palazzo waterside entrances. Palatial interiors illuminated above give the regal façades a depth lacking during the day. After disembarking at the top of the canal, I crossed the Calatrava bridge in a windy drizzle. Fiber-optic lights concealed in the bronze handrail, and lights from below, gave the glass balustrade a soft gleam. Covered with raindrops, it glistened as well. In 2002 the bridge was only a model displayed at the eighth Biennale, but now, when the other exhibits go, this one is here to stay as part of classic Venice.

Until November 23. For information, visit labiennale.org.