Followers of South End's emergence over the past 15 years from industrial blight to urban chic will witness another evolutionary twist early next year.

That's when one of the first commercial developments to jump the thriving business district's western boundary will open at South Tryon Street and Tremont Avenue.

Citispace in South End is taking shape on 3 acres as an architecturally themed cluster of offices and showroom condominiums that will include a renovated building and two new ones.

With this project, co-developers Citiline Development & Ventures and The McAllister Group, are introducing South End business owners to a typically suburban concept: the gated office campus.

The buildings, a courtyard and roughly 130 parking spaces will be enclosed behind a decorative metal fence and electronic gates.

"The buildings will be along the street, and most people probably won't even notice the gates," said Citiline's Tim Crawford. "It will be secure, but it won't feel like a fortress."

That sense of security and the project's relative abundance of parking in the tight South End market are selling points, but the developers believe their architectural blend of modern glass and steel with traditional brick also will have appeal.

The project will include a 17,000-square-foot renovated building that dates to the 1940s. It will also include new buildings of 12,000 square feet and 10,000 to 12,000 square feet.

"The buildings are similar in concept and style, but almost all are individually unique," said Doug Stephan, whose Vision Brokerage Group is handling sales.

The old building, for example, has tall, bowed ceilings with skylights and sandblasted brick and wood.

One of the new buildings will feature a curved glass-and-steel unit that will become the project's architectural focal point.

Citispace is about a block south of another edgy project -- MECA Properties' multicolored Camden Square Village commercial condominiums on the opposite side of South Tryon at West Worthington Avenue.

Crawford said South End's emergence in recent years as a design center and home furnishings hub convinced him the timing was right to steer development across Tryon.

"Someone has to go out there and be the pace setter and look a new horizons and new territories," he said. "I think that's what this project does."

South End redevelopment began along South Boulevard between uptown and Tremont Avenue, but with the anticipated arrival of light-rail transit in 2006, it's spreading in all directions.

As Citispace and Boulevard Centro's Wilmore Walk residential condos on West Worthington Avenue on the west side of South Tryon change the landscape, owners and developers can envision a more expansive South End.

Wilmore neighborhood leaders have been supportive, too, encouraging revitalization west of South Tryon and seeking links to South End's business hub, trolley stops and future transit stations.

Crawford hired Charlotte's Liquid Design as architect and Narmour Wright Associates as interior designer with the goal of visually meshing trendy Citispace with Camden Square's distinctive metal-sided buildings and South End's older brick structures.

He believes Citispace can become a southern gateway to Wilmore and spur more commercial development along South Tryon between West Boulevard and Remount Road.

"I know of two pieces of property on that side of Tryon Street that have already gone under contract," he said. "I don't know what they are planning, but I doubt that would have happened without this kind of project close by."

Citispace, valued at about $5.2 million, will include more than 40,000 square feet of offices and showrooms.

Crawford said the renovated building -- he calls it Building A -- is nearly sold out with buyers committing to about 80 percent of the space.

The two remaining units -- about 1,500 square feet each -- are listed for just under $200,000, he said.

Buyers include Citiline, which will move its offices there; The McAllister Group; McDade Supply; Metro Masonry; Affinity Plus and an undisclosed investor.

The owners are expected to occupy the building in January.

Crawford said many of the initial buyers liked the site's proximity to South End's growing design, home furnishings and construction district.

The developers are preparing to start work on 12,000-square- foot Building B, to be finished early next summer.

Buyers have reserved about 40 percent of that space, Crawford said.

No construction start date has been determined for Building C.

Crawford disclosed plans for Citispace about a year ago after passersby noticed workers sandblasting the exterior of the existing building, next to Tremont Music Hall.

Gregg McAllister said The McAllister Group joined Citiline in developing the project after the real estate and contracting firm looked there about six months ago for office space.

The McAllister Group now is Citispace's general contractor as well as co-developer.

South End has come a long way. It seems like only yesterday that MECA Properties President Tony Pressley was trying to convince city leaders that aging industrial buildings along South Boulevard could enjoy a new life as offices, shops and showrooms.