San Diego

After almost seven months of construction, workers Wednesday hoisted the last steel beam to top off the 499-foot Symphony Towers office tower--the tallest building in San Diego County.

The beam was signed by most of the 200 iron workers who helped build the framework for the 34-story office tower and the adjacent 24-story Marriott Suites hotel. Attached to the beam were an American flag and a small tree, which signified that no injuries or deaths have occurred during construction of the $143.5-million project.

Atop the taller building, representatives of Charlton Raynd Development Co., which heads the project, joined workers to celebrate. Completion of the office building is set for early 1989, and completion of the hotel will follow a few months later.

The 1.1-million-square-foot project will surround Symphony Hall and cover the entire block bounded by A and B streets and 7th and 8th avenues. The hall has been in use throughout the construction.

So far, developers have leased over 40% or 200,000 square feet of the office building’s 516,000 square feet of available space to three major tenants--the accounting firm Peat Marwick Mitchell & Co., the Los Angeles-based law firm Gibson, Dunn & Crutcher and AT&T.;

Douglas Wilson, managing general partner of Charlton Raynd Development Co., said that more than 50% of the office building’s space will be leased within several weeks.

“Today’s gathering was for the iron workers,” said Wilson. “It’s a tradition for them to celebrate the topping of a building, especially when no accidents have occurred.”