Warren is a city in and the county seat of Warren County, Pennsylvania, United States, located along the Allegheny River. The population was 9,404 at the 2020 census. It is home to the headquarters of the Allegheny National Forest and the Cornplanter State Forest. It is also the headquarters for the Chief Cornplanter Council, the oldest continuously chartered Boy Scouts of America Council, and the catalog company Blair. Warren is the principal city of the Warren micropolitan area.

The Pittsburgh-Des Moines Steel Company, and often referred to as Pitt-Des Moines Steel or PDM was an American steel fabrication company. It operated from 1892 until approximately 2002 when its assets were sold to other companies, including Chicago Bridge & Iron Company. The company began as a builder of steel water tanks and bridges. It also later fabricated the "forked" columns for the World Trade Center in the 1960s, and was the steel fabricator and erector for the Gateway Arch in St. Louis. A number of its works are listed on the National Register of Historic Places.