Aecom Technology Corp. late Wednesday said that it acquired Tishman Construction Corp. in a cash-and-stock deal valued at $245 million.

Tishman is a private New York provider of construction management services that also does a lot of business in the United Arab Emirates. It built the original World Trade Center in New York City and the recently completed MGM Mirage CityCenter in Las Vegas.

Aecom, a downtown Los Angeles provider of professional technical and management support services, said the acquisition expands its mix of higher-margin construction management and program management work.

“This is a unique opportunity that combines two best-in-class industry leaders to form a fully integrated global platform capable of delivering the full suite of services – from project concept to completion,” Chief Executive John M. Dionisio said in a statement.

The transaction will be paid in cash and Aecom common stock, with the cash portion coming from proceeds of a recent $250 million debt issue. The transaction closed earlier Wednesday.

Tishman has 900 employees worldwide and generated revenues of nearly $1 billion in 2009. Current projects include two World Trade Center tower reconstruction projectsm the new headquarters of the U.S. Food and Drug Administration in Washington, D.C. and the Angsana Resort & Spa in Abu Dhabi.

Tishman also is in a joint venture with Aecom for the first phase of the U.S. Department of Homeland Security’s new headquarters in Washington, D.C.

“We have worked in partnership with Aecom for many years and now look forward to Tishman becoming the cornerstone of Aecom’s construction management practice,” said Tishman Chief Executive Dan Tishman, who will continue to run Tishman’s operations and join the Aecom’s leadership team as a vice chairman and director.

Prior to the announcement, Aecom shares closed down 17 cent, or less than a percent, to $24.17 on the New York Stock Exchange.