Henry N. Cobb. Photo courtesy of Pei Cobb Freed & Partners

Henry N. Cobb, the groundbreaking architect and longtime collaborator with visionary designer I.M. Pei who crafted Boston’s most iconic tower, died yesterday at 93.

Cobb’s death was confirmed by his firm, Pei Cobb Freed & Partners, in a post on its website. Cobb founded the firm along with Pei and architect Eason H. Leonard in 1955. Pei himself died last May.

“Over a career that spanned seven decades of sustained and brilliant accomplishment, his breadth of engagement and depth of insight guided generations of architects,” firm partners Michael D. Flynn, Ian Bader, Yvonne Szeto, Michael W. Bischoff and José Bruguera said in a statement. “Unwavering in his commitment to both attainment and restraint, Harry lifted our art to a definition of truth itself.”

Cobb’s many buildings included Boston’s Harbor Towers and the landmark John Hancock Tower, now known as 200 Clarendon, in Boston’s Back Bay. The building was one of the first towers to employ a reflective glass curtain wall, but suffered teething troubles. The building’s movement under high wind and solar heating and cooling loads caused dozens of the structure’s innovative 4-foot-by-11-foot glass panels to come crashing to the ground. As panes of glass fell out and were replaced by temporary plywood sheets, the building became known as the “plywood palace,” with its opening delayed from 1971 to 1975 and its cost escalating by several million dollars.

A solution was found by replacing nearly half the 10,344 window panes with panes of a different design in 1973, at a cost of $5 million to $7 million.

Since its construction, the building became Boston’s most iconic tower and helped to define Back Bay’s “high spine,” which helped fuel decades of subsequent development. Late in his career, Cobb returned to Boston to add one more punctuation mark to its skyline: the One Dalton luxury hotel and condominium tower, which opened last year to public acclaim.