Like a dowager receiving homage from younger generations, the bright, white facade of downtown Dallas's restored and revamped Union Depot stands regally before the new silver-glass-walled, 1,000-room new Hyatt Regency Hotel and the 50-story dome-topped tower restaurant and observation point of the developing ReUnion complex.

More and more, people are thronging to this west-end enclave of the newly awakening "after 5" downtown Dallas area.

Passengers walking from Amtrak or the Hyatt Hotel through the underground corridors dotted with potted plants emerge at the entrance to the depot's ground floor, where they are greeted by a benignly smiling, 10-foot-high bronze statue of a Texas Ranger.

The corridor is as plush as today's airports, its earlier-era, white-tile walls covered with mushroom-colored carpeting, its ceilings updated with silver polished metallic squares. There the ambience is a far cry from the 1914 decor of the depot's original splendor, but up the escalators, the faithfully retained nostalgia remains in what used to be the mahogany pew-lined waiting room, justifying Union Depot's place in the National Register of Historic Places.

Adding a hospitable and homey touch are the scattered wooden slat benches with wrought-iron supports.

To the west the traffic hums by the underpass, the gateway to Fort Worth, with the buzzing mid-cities of the Metroplex lining the highways between. Centering them is Dallas-Fort Worth Airport, whose Surtran buses ferry passengers back and forth from Union Depot. Also on the depot's ground level are Amtrak's ticket counter, Avis Rent-a-Car and the brochure-laden Visitors Information Center, manned by Dallas Chamber of Commerce information specialists and volunteers for the Committee for Foreign Visitors of the Dallas Council on World Affairs.

At the top of the connecting ReUnion Tower is the NBC affiliate station, KXAS-TV, and flower and gift shops, boutiques, galleries, and professional offices of geologists, attorneys and architects are already settled or coming in. On the second floor, under the 48-foot vaulted ceiling, are various food kiosks and a 1920s-looking resplendent restaurant which gives the whole its name.