The Loudoun County school system is preparing to open a $26 million, five-story, brick and glass administrative headquarters in Ashburn on Monday -- a symbol, school officials say, of the county's suburban transformation and commitment to government services.

But its multimillion-dollar price tag also has drawn criticism from taxpayers concerned that the school system is paying too much for offices at a time when it is building schools and hiring hundreds of teachers to accommodate growth.

The new building will replace the school system's Leesburg headquarters, located in a converted school built in 1925. School administrators have complained for years about crowding in the building, which is hemmed in by narrow roads and a historic cemetery.

Loudoun is not the only school system in the Washington region looking for new space for its administrative staff. In December, Fairfax County officials will move into a recently purchased 210,000-square-foot office building, with enough land to build another similarly sized building next door. In Montgomery County, a school official said the district is looking for sites that could replace its main offices in a former Rockville high school.

But in Loudoun, where school enrollment has shot up from about 20,000 to more than 47,000 in the last decade, the new building is seen as a sign that the district is outgrowing its rural roots. The office space will consolidate workers not just from the crowded Leesburg school but from three other sites around the county. With 167,000 square feet, there will be room to spread out as well as space to accommodate new hires for the system, which is expected to exceed 60,000 students by 2009.

"This really makes a statement about the change in Loudoun County public schools," said School Board Chairman John A. Andrews II (Potomac). "For years, we've been a suburban but largely rural community. With the growth we've had, we're now becoming one of the largest school systems in the state."

The new headquarters has 23 conference rooms, two staff break rooms on each floor and a top-floor library with floor-to-ceiling windows. Inset on the building's brick facade is a nine-foot color replica of the school system's seal. The School Board meeting room, now a converted gym in Leesburg, will be a high-ceilinged auditorium with state-of-the-art audiovisual equipment and a seating capacity of 760.

Those kind of details have led to complaints about the cost. Questions also have been raised about a 2001 decision by the Board of Supervisors to finance the project without a voter referendum. In 1999, voters turned down funding for an expansion of the current headquarters.

"The size is enormous," said Donna Fortier, who is on the board of a nearby Ashburn homeowners association. "My understanding is they're looking to bring in the departments so they're not scattered. That makes complete sense to me. But that has some residents angry, that our tax dollars are being spent on this huge, gargantuan building."

Supervisor Bruce E. Tulloch (R-Potomac), who was elected after the project's approval, said the building had to be nicer -- and more expensive -- than necessary because school officials decided to put it in the middle of a housing development, where residents would have to see it every day.

"Did it have to be as ornate as it is? No," he said. "It has some details I think are a little opulent for a school building. But because they picked that site, those features had to go in."

The design of the boxy building, which towers over the tree line and a major county thoroughfare, has also come under fire. Supervisors approved the plans over the objections of the county's Planning Commission, which complained that it was oversized and unattractive.

Andrews, however, said he thinks the structure looks "just fine," given that it was built with taxpayer dollars. And he insisted that the school system got a good price, especially since the building should be sufficient for several decades.

"The administration has to go somewhere, and this was put off for years and years and years," he said.

Loudoun County is moving its school offices from a crowded former school building built in 1925 that is adjacent to a historic cemetery in Leesburg.

The school system's new $26 million headquarters in Ashburn cost too much, critics say.