Casper Samuel Neer, 60, an architect who won an outstanding urban design award from the Department of Housing and Urban Development for his design of the Market Square Plaza in Alexandria, died at his home in Alexandria Wednesday after a heart attack.

At the time of his death, Mr. Neer was a member of the architectural firm of Neer and Graef and was engaged in the restoration of the Alexandria City Hall and the old Fairfax County Courthouse. Over the years, he had designed a number of churches, schools and houses in the Washington area. He won an award for his design of the Natural Gas Pavillion at the Seattle World's Fair of 1962.

Mr. Neer was born in McClave, Colo., and grew up in Austin, Tex. He earned a bachelor's degree in architecture at the University of Texas. During World War II, he was commissioned in the Navy and assigned to landing craft. He took part in the invasions at Salerno and Anzio in Italy and at Normandy in France. He commanded at LST during the invasion of Okinawa in the Pacific.

After the war, he went to Harvard University, where he earned a master's degree in architecture, studying under Walter Gropius. He practiced in Boston until 1954, when he moved to Annapolis. He later moved to Alexandria.

Mr. Neer had been a member of the Baltimore Design Advisory Panel since 1964. He also was a member of the Alexandria Urban Renewal Review Panel and was a consultant to the City of Alexandria on its Gadsby urban planning project. For 12 years during the 1950s and 1960s, Mr. Neer taught architecture at Catholic University.

He was a member of the American Institute of Architects and had served on various of its committees.

Survivors include his wife, Kay Larson Neer of Alexandria; one daughter, Brooke Neer Heiberger of Richmond; three sons, Michael Chiles Gardner Neer of Rochester, N.Y., Thomas Morgan Neer of Honolulu, and John Adams Neer of Alexandria, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Hospice of Northern Virginia, Arlington.