As it stood, the plaza comprised four elements, three of which are now gone. The hotel tower, which still stands, was originally part of an elaborate spatial relationship that began below ground and continued to the top of the high-rise. At the bottom was the sunken ice-skating rink, set in an open plaza. At the edge of this courtyard was the famous hyperbolic paraboloid, a pyramidal glass-and-steel concoction that really sang. And climbing above the paraboloid was the chaste, multi-story box that once served as a department store. All three of these elements led the eyes up to the hotel tower in a joyful arc.

The relationship of the vertical high-rise to the horizontal low-rise buildings and open courtyard was a Pei signature. His approach has been copied by architects everywhere.

Once one of the city's premier spots, Zeckendorf Plaza had fallen on hard times by 1994, when it was picked as the most likely spot for a new hotel to bolster the flagging CCC. The department store was vacant and the hotel, a Radisson, was in a dingy and somewhat neglected condition. After a heroic struggle to save the plaza, led by Historic Denver and endorsed unanimously by the Denver Landmark Preservation Commission, the city council folded -- as usual -- and in 1995, one of the city's finest examples of modern architecture was turned into hamburger.

The hotel is still standing -- as part of the Adam's Mark hotel -- but it has suffered the indignity of a garish interior redo and has been resurfaced on the first floor, where a protuberance of a new porte cochère has been appended at the main entrance. The courtyard is now a driveway, and the hyperbolic paraboloid has been replaced by an ugly neo-traditional storefront design that is a shameful use for all that good granite. The box has been popped a few floors and is now clad, Vegas-style, in black reflective glass.

These changes were paid for in large measure with public money. Fred Kummer, the out-of-town developer who built the Adam's Mark on the mutilated carcass of Zeckendorf Plaza, got $25 million in Denver Urban Renewal Authority money. (To get a feeling for how wonderful the plaza used to be, catch a glimpse of it from the back, on the Civic Center side, where the ugly changes are mostly hidden -- aside from a poorly designed Adam's Mark sign.)

But the renovation of the Adam's Mark wasn't even complete when, in 1996, the Denver Metro Convention & Visitors Bureau called for something else to help bolster the CCC: a 1,000-room convention headquarters hotel.

Hey, what a minute -- wasn't that why Zeckendorf Plaza was mauled?

Well, it turns out that the Adam's Mark, like the CCC, just isn't big enough.

This led to the next destructive episode: the 1998 demolition of the old Denver Post Building, a 1949-1950 terra-cotta, marble and aluminum moderne structure by Denver's famous Temple Buell (the architect, not the theater he paid for) that sat across from the CCC on 14th Street. Even before he bought the building, developer Bruce Berger sought an exemption from a moratorium on downtown demolition that is supposed to stop the creation of new surface parking.

Even though he already owned a number of surface parking lots, Berger convinced the city council that parking was only an interim use. The Post building needed to go, he said, not to provide room for cars but to make room for a new convention headquarters hotel. There was no developer for this dreamed-of hotel, but if the city was willing to put up, say, $50 million, Berger might convince someone to do it. Again Historic Denver and the landmark commission mounted a valiant fight, only to be crushed by their wealthier and therefore more powerful foe.

Let's review. As a direct result of the CCC, Denver has so far lost the historic Silver Triangle neighborhood, an I.M. Pei masterpiece and a Temple Buell gem.

And if the promoters of the CCC expansion have their way next Tuesday, things are going to get much, much worse. At stake is the very character of the city.

The addition is planned for the current site of the fabulous 1969 Currigan Exhibition Hall, which, like Zeckendorf, is one of the city's greatest architectural assets. Sadly, there has been no preservation struggle waged over the fate of Currigan. It was defused with a preposterous suggestion, endorsed and promoted by the National Trust for Historic Preservation, to dismantle and move the building. This bold plan, which is technically possible but not feasible, lulled preservationists into a kind of denial of the fact that the building is actually headed for the wrecking ball. Who could blame them for not having the heart to face another doomed campaign?