HACKENSACK, N.J.--From a distance, it could just be another of the monstrous structures--oil drums, refineries, and the like--that populate the North Jersey neighborhood. Upon closer inspection, however, it turns out to be about the most impressive monument to the multi-million dollar phenomenon known as professional football ever to be constructed on Route 3 in Hackensack.

Where 76,500 Giant fans sat on Sunday, there was once a Giant fen. East Rutherford, New Jersey residents, in fact, never envisioned a big-time football stadium in their private bog--they had in mind a couple of factories, maybe a sewage plant, or something. But a few years back, then-Jersey-governor William Cahill and a bunch of guys he assembled into an outfit known as the "New Jersey Sports and Exposition Commission" headed by Sonny Werblin, came along, and were so taken by the idea of bringing professional football to the financially troubled state that they decided they would spare no expense, make no compromise.

The $30 million stadium was consequently built in tandem with a mammoth harness racing circuit; its primary function at this juncture in its history is to pay off the substantial debt which the state must foot almost exclusively--oh, yes, the Giants pay no property taxes in Jersey.

Brendan Byrne, the current tenant of the Trenton state house, spry, ruddy, athletic-looking, exuding Charlton Hestonesque virility, stood in one of the mezzanine prestige-boxes which ring the new stadium on Sunday, wielding a soggy ham and cheese sandwich in one hand and glad-handing fellow celebs with the other.

Byrne, like the 76,500 New Yorkers who joined him at Hackensack for the new-lease-on-life home opener, came not really to see the Giants win, not really to see the Giants play, but instead, simply because it was an event (read: EVENT) and you had to be there.

The Giants aren't even the New York Giants anymore, even though they really are (something of a travesty, something of a shame), and they really just don't have it in them to win anyway. It was an event, a big event, like the wedding of a distant cousin, and you had to be there.

Up with People--you could hear the kids on the field singing it as you made your way up one of the six express escalators that whisked you to your final destination without so much as a stop to catch a view of the New York skyline across the river.

Up with People--the pedestrian walkways which ring the stadium must be at least 50 feet wide--at least twice as wide as those at the old Yankee stadium. Music--yesterday it was, of course, "Up with People,"--is piped continuously into the bathrooms, which are equipped with self-flushing urinals.

The field is a miracle of modern Astroturf-cultivation. Nothing separates it from the carpeting in a Mather House room except for its color--it remains the traditional green. It also slopes down on both sides from midfield to allow for optimum drainage.

Fans are accommodated in seats, not surprisingly, all of which are leatherette-plastic and, happily, boast great sight lines and visual access to blow-up instant replay screens at either end of the field.

Hots dogs are long, lousy and cost 85 cents. Nice people--who look like Disneyland guides--run around with megaphones trying to palm off lost little boys and girls. They're nice, and they're definitely up with people-people.

On the Mezzanine level Sunday, tuxedoed, pleasant, up-with-people-looking servants patrolled around with trays of hors-d'oeuvres oblivious to the pilferers who reduced them to hopeless shambles of parsley and potato chips within minutes.

Bob Hope circulated through the crowd, wearing a smile, and a "Kiss me, I'm Irish" button.

He walked into one of the boxes and shut the door, leaving news photographers on the outside. A woman asked one of the photogs, "Who was that?"

"Telly Savalas," he replied. She fairly swooned.

Oh, yeah--on the field, there was a steady parade of the famous and not-too-famous: there were the six remaining original 1925 Giants--one of whom is, somewhat disconcertingly, currently confined to a wheelchair. Then there were the '56 Giants--Katcavage, Gifford, Rote, Grier, Connerly--still on their feet and looking like they could still put on the ol' uniforms in a pinch.

The '76 Giants did just what was expected of them--they fell down at the feet of the Dallas Cowboys, who also play in a pretty new stadium, but enjoy the estimable privilege of deserving it.