A Mexican engineer who initially specialized in building concrete shells, Francisco Castaño Sr. was first to realize the potential for enlarging the size of domed structures using Arthur Fentiman's unique connector.

Castaño introduced the use of the Fentiman connector in long span applications, gaining economies and flexibility. Castaño and his firm built the first metallic shells that deviated from the Geodesic sphere, introducing hyperbolic and elliptical paraboloids, and free-style structures. The work he completed from the 1960s to the 1980s was groundbreaking.

Castaño and Douglas Wright collaborated for many years, creating a body of work that remains the standard for originality, integrity and applicability in dome design and construction.