After years of costly delays and political infighting, the crown jewel of the new World Trade Center complex will finally be open for business Monday, welcoming its first wave of workers.

About 175 employees from anchor tenant and publishing giant Condé Nast — whose employees include Vanity Fair’s Graydon Carter, Vogue’s Anna Wintour and the New Yorker’s David Remnick — will move into offices on floors 20 through 44 of the 104-floor “Freedom Tower,” officially 1 World Trade Center.

Although they won’t have access to the 1,776-foot skyscraper’s breathtaking 102nd-floor observation deck before it opens in the spring, the new tenants are happy to be part of lower Manhattan’s latest chapter.

“Condé Nast is proud to be a part of this important moment of renewal for the city of New York,” said Condé Nast spokeswoman Patti Rockenwagner.

“We are excited about contributing to the vitality of this community for years to come.”

Rockenwagner said the 3,400 staffers who are slated to move will not relocate all at once. The company is planning to move in stages from its Times Square offices with plans to fill its new home by the end of February.

New Yorkers and tourists celebrated another milestone in the area’s remarkable comeback.

“It’s a beautiful thing,’’ said a construction worker Sunday at the WTC site, where he has toiled or 12 years. “People were depressed from before. Now, they are more happy that they see a positive change.’’

Krisy Steelman, 35, who was visiting from Georgia, said the tower’s opening is important for the entire country.

“I think everyone will be excited about that,” Steelman said. “It symbolizes growth, renewal, a fresh start, the unity of our country and what we’re able to do. I’m glad we live in a county where if something bad happens, we are able to make it better.”

Also new to the neighborhood is a battalion of added police officers. Nearly 50 Port Authority cops patrolled the area in the days before 9/11. That number has since doubled, with plans for up to 200 by the time all the signed tenants move in.

The tallest building in the Western Hemisphere, which cost $3.9 billion to build, was originally scheduled to open in 2006, but cost overruns and political infighting caused several delays.

Condé Nast was one of the first major tenants to sign a lease. Other tenants include the General Services Administration and the advertising firm Kids Creative.

Although the Port Authority, which owns the tower, has hailed the opening, only 60 percent of the building has been leased, which has observers worried.

But some New Yorkers said you can’t put a price on freedom.

“It’s incredible that it’s back in business,” said Ilene Danuff, 55, of Chelsea, who works in advertising. “We brush ourselves off and move on. It shows that it’s a resilient city with resilient people, and I’m happy to be in New York.”