The Penguins have let their development rights for the Lower Hill expire — leaving the future of the project up in the air. The Penguins’ development arm, Pittsburgh Arena Real Estate, has let its option to build on the rest of the Lower Hill expire, returning control of the land to the city’s redevelopment authorities. The Sports and Exhibition Authority and Urban Redevelopment Authority say they’ll now reassess the project through a “transparent public process.” The $230 million FNB Financial Center is complete, and a 4,000-seat entertainment venue is underway, but much of the 28-acre site remains vacant. In a statement released to KDKA Radio Mayor Ed Gainey called the expiration “an enormous opportunity” to reset the project and ensure redevelopment “repairs historic harm” and promotes “equitable growth that rejects gentrification.” The Penguins say they plan to remain engaged as partners in shaping the next phase of the site’s future.