Through those street entrances to the hub, the Oculus reveals itself all at once from awkward, tongue-shaped balconies. Mr. Calatrava gives the whole view away. The trip downstairs becomes a letdown. It’s better coming up from the PATH trains, where riders pass through a kind a vestibule (beneath the tracks for the No. 1 train) before stepping up to the nave of the Oculus, which appears suddenly, obliquely. It may put you in mind of entering the Guggenheim, with its sequence of compression and release, except there, space continues to unfold and surprise you along the ramp.

In its scale, monotony of materials and color, preening formalism and disregard for the gritty urban fabric, the hub is the sort of object-building that might seem at home on the Washington Mall. Its cramped mezzanine, where daily life should thrum, precludes the sort of bars and restaurants that have made the terraces at Grand Central a destination and heartbeat of the neighborhood. Westfield Group, which oversees retail at the hub, doesn’t intend for there to be cafes with tables spilling across the floor of the Oculus. So the hub clearly won’t be like the Galleria in Milan or the Piazza San Marco in Venice. Or even like the Hauptbahnhof in Berlin.

I toured the site recently with an architect who admired Mr. Calatrava for sticking to his guns and conceiving an ambitious public space. Cost was the Port Authority’s responsibility, he said, and besides, cost isn’t value, all of which is true.

Mr. Calatrava has given New York something for its billions. But if the takeaway lesson from this project is that architects need a free pass, a vain, submissive client and an open checkbook to create a public spectacle, then the hub is a disaster for architecture and for cities.

Follow Michael Kimmelman on Twitter: @kimmelman

The World Trade Center Transportation Hub can be reached by subway: Take the 2 or 3 train to Park Place, and then walk west. Or you can take the PATH!