However, it is possible to say that the windows in the new tower offer far wider panoramas (even of the fog) than those of the old trade center observatory, which were divided into deep, narrow bays between columns. And an interactive mobile tablet, rentable for $15, makes orientation easy no matter the weather, as the screen clearly depicts and annotates whatever part of the skyline one is facing.

It is also possible to caution acrophobes in advance about the 14-foot-diameter “sky portal,” which looks as if it is suspended over the streets below, like the Ledge at Willis Tower in Chicago. The portal’s glass floor is actually looking down on two dozen high-definition screens carrying a live feed from cameras mounted at the base of the building’s spire. But the illusion is unnervingly convincing.

And it does not seem far-fetched to predict that the bar seats facing the Hudson River on the 101st floor may soon be among the most coveted in New York, though Steve Cuozzo, the restaurant critic at The New York Post, has complained that one cannot dine or drink there without paying the admission fee, because the 60-seat steakhouse and the more casual 100-seat cafe and bar and grill are within the observatory.

(In the original World Trade Center, the Windows on the World restaurant was in the north tower. The observatory, which included an open-air rooftop deck, was in the south tower. There is no outdoor deck at One World Observatory.)

The fog compelled us to focus on the design of the observatory, which Legends, as the operator and developer, created with the architectural firm Montroy Andersen DeMarco and designers and producers at the Hettema Group and Blur Studio.