A complex and controversial redevelopment project including a new school, park, fire station, affordable-housing building and two residential-retail high-rises in the western Rosslyn neighborhood won final approval from the Arlington County Board on Saturday.

When the entire project is finished in the early 2020s, the “superblock” along the north side of the 1500-1600 block of Wilson Boulevard will be split in two, the century-old Wilson School will be replaced with a contemporary, fan-shaped 775-student school and an aging fire station will be rebuilt, tucked into the ground floor of a new retail-residential tower.

That’s not even mentioning the most controversial segment — the replacement of the small and heavily used Rosslyn Highlands Park — or the replacement of the low-rise Queen’s Court residences at 1801 N. Quinn St. with a 12-story apartment building that includes 249 affordable-housing units.

Few developments better illustrate Arlington’s transition from what was once a small suburb dominated by single-family homes and garden apartments to an urban community with high-rise apartments, sidewalk-level retail stores and intensely developed green spaces. Students will be strongly urged to take Metrorail, buses or bicycles to get to classes; their school rooftops will include space for instruction and recreation; and at least for the first few years, a temporary fire station will occupy what will eventually be their athletic field.

The last major sticking point Saturday was whether the county would delay approval of a 93-space parking garage beneath an athletic field at Quinn and 18th streets.

Penzance Properties, the developer of the residential high-rises, offered the schools 100 free parking spaces in its garages, and the county manager’s staff suggested that the underground garage might not be needed, saving the school district about $5 million on its $108 million school.

But Nancy Van Doren, the school board chair, argued that teachers, staff, parents and visitors to the school need about 150 spaces. The school district had no guarantees that spaces in the private garage would be easily accessible at all times, Van Doren said.

Nevertheless, County Board members voted to delay the construction of an underground parking garage and to try the 100 garage spaces to see whether those spaces are adequate.

The County Board also wrestled with elevator access from the private garage to the park, and an accessible school entrance that forces the athletic field to tilt up at one end. But board members praised the 180,000-square-foot school’s design by the Bjarke Ingels Group and Leo A. Daly. The school district expects significant community use for the building.

“I wanted a lot more park and open space out of this project,” said board member Christian Dorsey (D). “[But] by trying to fit so much into a fairly limited area, there are going to be compromises all around.”

Nearly every piece of the plan, known as the Western Rosslyn Area Planning Study, drew heated debate over the past four years, starting with a secret letter of intent between the county and Penzance, which allowed the developer to lease county-owned land beneath the existing fire station and take a portion of the park for its own use.

Neighbors strongly objected to the impact of the development and the school on their local park. Historic preservation advocates unsuccessfully fought to save the 107-year-old Wilson School, which will be demolished for the new school containing the H-B Woodlawn Secondary Program and the Stratford Program. They lost twice.

Students fought for a full outdoor field for sports and recreation; parents of students with disabilities who attend Stratford argued for buses to have ground-floor access to the school. The county manager, seeking a temporary location for the fire station, suggested putting it on another park, which triggered that neighborhood’s opposition. The County Board eventually decided to put it on the new school’s athletic field.

The Penzance buildings will hold 892 new residential units as well as ground-floor retail space.

The board also voted to approve the replacement of 39 low-cost garden apartments at Queen’s Court with 249 committed affordable-housing units. The property will also contribute a 9,000-square-foot park easement with a children’s playground.