In a unanimous decision, the Rockville City Council this week adopted an extensive, long-range plan aimed at revitalizing the city's business district.

Known as the Town Center Urban Design Plan, it calls for redevelopment of the area surrounding the city's downtown mall, the Commons at Courthouse Square, major landscaping throughout the 423-acre Town Center area and private development of a hotel, conference center and residential housing.

The decision came after almost two years of planning and more than a decade after much of the city's downtown was razed to make way for a shopping mall. The mall failed to attract major department stores and became the focus of the city's negative image, city officials maintain.

The plan, which will cost about $4 million to implement over the next 15 to 20 years, was designed by architect Arthur Cotton Moore. Moore is known nationally for his ability to transform blighted urban areas into prosperous shopping, residential and entertainment showplaces.

This week's decision was nearly delayed after council member Kenneth Sullivan moved to amend the zoning ordinance to permit residential and commercial development on the Rockville Drive-In site on Hungerford Drive.

Under the new plan, only residential development would be permitted on that parcel of land.

Sullivan's move sparked the ire of council members, who called it an attempt to undermine the two-year planning process that had included numerous meetings with citizens.

At an earlier council meeting, Sullivan voted against the same amendment he made Monday night. He maintained his new motion was made "after being given new information about the area."

Mayor William E. Hanna Jr. threatened to table the motion to adopt the plan and to reopen public hearings on Sullivan's amendment.

"You're shooting from the hip after we've spent two years doing this," Hanna told Sullivan."At the last minute to propose some major change . . . it's terrible for the city."

Sullivan's motion failed but not until the other council member criticized Sullivan, who is the sole representative on the council from the group known as the Alliance for Rockville. Hanna and other council members belong to the Independents for Rockville.