Corporate Office Properties Trust is a real estate investment trust that invests in office buildings, primarily in the suburbs of the Washington, D.C. metropolitan area and primarily leased to the U.S. government or companies in the arms industry.

As of December 31, 2016, the company owned 164 office properties totaling 17.2 million square feet, 11 office properties under construction, and 1,028 acres of land held for development.

The company's largest tenants are as follows:

The company was founded in 1988 by Clay W. Hamlin III as Royale Investments, Inc.

In 1991, the company became a public company via an initial public offering.

In 1997, the company merged with Shidler Group, founded by Jay H. Shidler, and changed its name to Corporate Office Properties Trust.

In 1998, the company acquired 16 buildings from Constellation Energy in exchange for a 41.5% stake in the company. Constellation sold its stake in the company in 2002.

In 2001, the company acquired an office complex in Chantilly, Virginia for $58.3 million.

In 2005, Randall M. Griffin became chief executive officer of the company. The company also acquired 6 one-story buildings in Columbia, Maryland for $26.0 million and 21 buildings in Baltimore County for $124.5 million.

In 2006, the company acquired 3 office buildings in Colorado for $43.6 million and a 55-property portfolio in Baltimore County for $362.5 million. The company also sold an office and retail complex in Baltimore for $20.3 million.

In 2009, the company acquired Canton Crossing for $125 million.

In 2010, the company acquired 2 buildings in Falls Church, Virginia for $43 million.

In 2015, the company acquired an office building in Baltimore, Maryland for $63.5 million.

In 2016, the company sold an office complex in Blue Bell, Pennsylvania for $142.7 million.

In 2017, the company announced the sale of assets in Virgnia for $53 million.