Disappointment is familiar to Eagles fans, so when two diehards took PATCO from South Jersey into the city Wednesday afternoon to see the gargantuan stage erected for the NFL draft, they tried to stay positive.

"Well, we got some exercise," said Frank Schuenemann, 70, of Mount Laurel.

"At least we didn't bring our cameras," said his buddy, Dominic Golden, 70, of Cherry Hill.

The men stood by a traffic light on Kelly Drive, craning to catch a glimpse of the eight-story "NFL Draft Theater" that has overtaken the stairs in front of the Philadelphia Museum of Art.

The stage is impressive by any standard.

"It's an engineering marvel," said Eric Finkelstein, the NFL's director of event operations.

Finkelstein said the theater was the biggest thing he had ever been a part of, and is the league's first three-tiered theater. It seats more than 3,000 people, with balconies on both sides, and is 310 feet wide and 220 feet deep.

One Electricians Local 98 foreman said the theater was easily the largest stage ever built in Philadelphia, with "tens of thousands of feet" of wiring hidden in its skeleton.

CSNPhilly cited an unnamed worker who claimed the stage was the largest ever built in North America. The NFL said it didn't know where the stage ranked worldwide, although Guinness World Records said the largest "temporary" stage ever built was for an art fair in New York in 2012.

That stage measured 275,007 square feet. The NFL did not release the square footage numbers for its theater, but based on its width and length, it's not a record-breaker.

C3, the contractor, obtained the required Philadelphia contractor license, according to Karen Guss, spokeswoman for the Department of Licenses and Inspections.

"L&I reviewed the plans for compliance with the Philadelphia Building Construction and Occupancy Code and issued a building permit," Guss said. "L&I is also requiring structural inspections, to be completed by a licensed professional engineer, throughout the construction process." 

Frank Keel, spokesman for John J. Dougherty, business manager of the Philadelphia Building and Construction Trades Council, said the construction unions "have been working around the clock the past two weeks to assemble the largest stage and fan experience in the history of the NFL draft."

Keel said electricians, stagehands, carpenters, laborers, riggers, and fitters have performed the majority of the work.

"There are literally miles of cable, above and below ground; a massive generator park out of sight but near the Art Museum; and enough lighting to be seen from miles away," Keel said.

He added that Dougherty wants the Eagles to take Alabama tight end O.J. Howard or Stanford running back Christian McCaffery with their first pick.

Finkelstein said the NFL fell in love with the Benjamin Franklin Parkway and was determined to use the museum's steps in the NFL Draft Experience.

Almost none of the theater was visible to the public Wednesday. Chain fencing and security funneled people around the venue. Golden and Schuenemann said the NFL Shop wasn't even open yet.

"They should have let us wet our whistle," Schuenemann said.

Click here for more coverage of the 2017 NFL draft in Philadelphia. Our live blog will have updates from the event starting Thursday at noon.

Few fans will see the labyrinth of rooms above and behind the stage, a maze of black cloth and blue and red lights, sectioned off for draft prospects and their parents.

One room features a printer that will emblazon a player's last name on his team's jersey seconds after he's picked.

On the stage, the NFL built foam columns that resemble the museum columns it's blocking.

The entire NFL Draft Experience, according to the league, is the largest fan festival it has created, about 25 football fields long.

Back on Kelly Drive, another tourist from South Jersey, Catherine Sampson, had a camera and tried to get a glimpse of the stage, but it was blocked by trees.

"I don't even see it," she said. 'Where is it?"

Sampson said she was unsure if she would return Thursday, when the draft begins.