Beyond the ephemeral glitter of a world's fair, the 2008 Zaragoza Expo, which runs through September 14th in the northern Spanish city, is architecturally memorable for only two or three innovative buildings. The compact 60-acre site along the Ebro River is designed to become a future urban district. Pavilions for participating countries (missing are Britain, Canada and the USA) and Spain's regions recede into the background with organic forms discretely designed by the Spanish firm ACXT. A landmark Water Tower structure by Enrique de Teresa, though organized as a double spiral of ramps around its central void, looks like an elegantly understated office building from a distance. At night, however, colored lights transform it into a spectacular virtual image of itself.

Photos courtesy Zaragoza Expo 2008 (top); © Javier Belver (above).

Ariel view of the 2008 Zaragoza Expo (top). Francisco Mangado's Spanish Pavilion (above).

The fair's two best buildings, the Congress Center by Madrid architects Fuensanta Nieto and Enrique Sobejano and Francisco Mangado's Spanish Pavilion, frame an animated clutter of attractions along the river. Boldly composed of a series of jagged clerestories, the Congress Center displays sobriety with an industrial, muscular, and sculpturally abstract design and spectacular interior spaces. Its only concessions to fashion are translucent sidewalls of expanded metal mesh and glass, which glow from within in the evening.

Mangado's Spanish Pavilion is conceived as a grove of 750 ceramic columns, which support the roof’s large shading plane and are interrupted by glazed exhibit spaces. The columns rise from shallow pools, and were originally intended to draw water via osmosis to cool the space through evaporation, but Mangado admits that mortar joints interrupt this process. No matter; the concept, conceived for the Expo's theme of "Water and Sustainable Development," is promising, and the result is visually fascinating.

Zaha Hadid's Bridge Pavilion is something of a disappointment. The structural concept, developed with Ove Arup, of a bundle of diamond-sectioned, multi-story tubes spanning the river in a gentle curve—like the tubular structural design of a skyscraper, but laid out horizontally—was promising, but the building lacks the sufficient transparency to convey this formal intricacy.

Other Expo buildings add color to the scene: the Pavilion of Aragon, the host region, shaped like a fruit basket and topped with inflatable vegetables for its rooftop nightclub; the River Aquarium, which features cascades of water down the full height of its facade; and the Citizen's Initiative Pavilion, the most ecologically sustainable of the Fair, shaped like a ceramic water jug and built of packed earth reinforced with wood, bamboo and straw. Also worthy of mention are the Hyberius Hotel, designed by Elias Torres and José A. Martínez-Lapeña, and the Third Millennium Bridge by engineer Juan José Arenas.