ARCHITECTURAL and urban history were made here recently with the opening of Zaha Hadid's first American building, the Lois and Richard Rosenthal Center for Contemporary Art. It is an amazing building, a work of international stature that confidently meets the high expectations aroused by this prodigiously gifted architect for nearly two decades. Might as well blurt it out: the Rosenthal Center is the most important American building to be completed since the end of the cold war.

Coincidentally, a comprehensive retrospective of Hadid's work opened last month at the Austrian Museum of Applied Arts in Vienna. Easily the most visually sumptuous architecture show to be seen anywhere in years, the exhibition puts the spotlight on a cluster of Hadid's recently completed buildings and other projects now moving toward construction. These include a train station in Strasbourg, France; a monumental ski jump, with lodge, in Innsbruck, Austria; a BMW plant in Leipzig, Germany; and a contemporary art museum in Rome.

The Iraqi-born Hadid, at 52, is crossing a threshold, in other words. Up to now, she has been known mainly for her lushly seductive paintings and drawings of unrealized projects, like the Peak Club in Hong Kong (1982) and the Cardiff Opera House (1994). Encountering a finished Hadid building -- in the round, at full scale, within a pulsing downtown setting -- is like meeting a new architect for the first time.

Hadid's renderings and models have already trained two generations to look at the city through different eyes. The Rosenthal Center performs a similar function for the body. It can be experienced as an exercise in heightening the mind-body connection, in fact. The design does not stint on visual spectacle. Inside and out, it presents vantage points of sufficient variety to keep photographers snapping happily for many years to come.