Cullinan Properties was founded in 1988 after Diane Cullinan Oberhelman entered the real estate business in 1980, beginning with office and industrial development in Central Illinois. Cullinan Properties operates as a full-service real estate development and investment firm, with work spanning mixed-use, retail, healthcare, office, government, and multifamily properties. Over time, Cullinan Properties expanded beyond its early base into a nationally active business developing, owning, and managing commercial and mixed-use projects across the United States. The company's portfolio includes destinations and facilities in sectors such as retail centers, medical environments, office space, government facilities, and residential communities.