County Board chairman J. Walter Tejada in the new gymnasium. ( Patricia Sullivan /The Washington Post)

The gym floor is polished, with markings for basketball, volleyball and pickleball courts. The weight machines in the fitness center smell new and are unmarked by scuffs. Tables in the reading lounge are stacked, awaiting a shipment of table legs but in the meeting rooms, other tables are up, some with computers ready for job training. Pool and foosball tables are ready for use.

The long-awaited Arlington Mill Community Center, rising like a modernist glass wedge from Columbia Pike’s western edge, opens Sept. 3 after five years of planning, interrupted by an economic crisis that forced a reboot.

But the 76,000-square-foot, five-story facility is coming in about $1 million under its $36 million budget, said George May, the county employee in charge of the center’s construction, as he led a tour of the center Monday.

“It was a huge effort ... a long project, it’s fair to say,” said J. Walter Tejada, Arlington County Board chairman. “This is a big deal. This is an anchor in an area that’s very diverse... It really means a lot to the community.”

The center is one of the important pieces in Arlington’s plan to turn Columbia Pike into a walkable, neighborhood-oriented Main Street. Utilities are being replaced, better lighting and sidewalks are going in and a streetcar line is planned. Last year, a major housing plan was approved which will increase density in the area but will retain the 6,000 affordable housing units that now define the area.

The sturdy construction and energy-efficient windows in the community center means that cell phones can’t get a signal in the building, but May said that will be corrected shortly. Residents can use wi-fi connections to the Internet in the building, and first responders will find a new robust location for emergency communications. The structure can be used for an emergency county shelter during disasters with the addition of a new generator.

One amenity the community insisted upon, Tejada said, was an outoor plaza where events, concerts and dances could be held. It’s right at the front of the building, along Columbia Pike at Dinwiddie Street and adjacent to a small playground for preschoolers. A Capital Bikeshare station will soon be installed on the other side of the permeable stone surface, convenient for trips on the nearby Four Mile Run recreational trail.

A wide variety of community groups, which have been dispersed to several other county and private venues, are ready to use the building, officials said. Fitness and folklore groups, English as a Second Language and citizenship classes, arts clubs and job training organizations have signed up to use the rooms. Northern Virginia Family Services will run an early Head Start program not too far from where senior citizens will gather for activities. Tiny child-height sinks and toilets are in the restrooms next to the pre-kindergarten rooms; a large commercial-grade kitchen is equipped to prepare meals for any group. The fourth floor is empty, ready for whatever needs arise.

Separately, the county has leased space on the ground floor street corner to the private, locally owned Pan American Bakery, which will set up a store there.

By the end of the year, more than 122 apartments with affordable rents are expected to open directly behind the community center. The Arlington Partnership for Affordable Housing is taking applications for its waiting list and lottery to get into the housing this week.

Getting the community center to this point has taken years. It’s on the site of a former Safeway grocery store, whose land the county bought in the 1990s. The Safeway was closed in 2007 and the County Board approved a mixed use building with a community center, residential and retail space in mid-2008.

The following year, the private developer working on the project withdrew after it was unable to secure financing for the job during the housing collapse. The county in late 2009 decided to build the coumunity center and underground parking on its own; ground-breaking was in August 2011.

Two of the construction surprises, May said, were when there turned out to be two foundations beneath the old Safeway. The other came after the state transportation department turned Columbia Pike over to Arlington County, and unmapped utility lines were found.

The roof of the 140-space parking garage serves as a podium for the affordable apartment complex going up above it. Parking in any of the 140 spaces dedicated to the community center will be free for the first four hours to accommodate people who volunteer or who take classes or stop in at the center. The center is also on multiple bus lines.

The construction and furnishing of the center is financed by two bond issues that brought in $28 million, $5 million in industrial development bonds from the federal government and $3 million in money carried over Arlington County’s budget from fiscal years 2009 and 2010.

The center will be open from 7 a.m. to 10 p.m. weekdays, from 10 a.m. to 10 p.m. Saturdays and from 1 to 9 p.m. Sundays.