After years of planning, the former Montgomery County Fairgrounds is being transformed into onMain, a “technology and innovation hub,” with investment from the State of Ohio and the property’s owners, Premier Health and the University of Dayton.
Check out this video for a look at the ongoing construction.
The site of Dayton events, from welcoming home the Wright Brothers to hosting the Montgomery County Fair for 165 years, the fairgrounds has long been an important gathering place and holds significant memories for residents of Farmersville and Germantown of livestock shows, rides, and great entertainment.
The land was purchased in 2017 and the Montgomery County Fair moved to its new location in Jefferson Township in 2018. Demolition of fairgrounds buildings began in 2019. The project stalled during the pandemic, with Premier Health using the site for parking and COVID testing.
Think Dayton building under construction on the corner of Main and Stewart Streets in Dayton, Feb. 2026
onMain Development
The first major project for onMain is the five-story, 120,000 square foot Think Dayton building, funded by a $35 million investment as part of the Ohio Innovation Hubs Program, designed to spur investment outside Ohio's major metro areas.
Rendering of planned Think Dayton building 📸 onMain
According to onMain, the Innovation Hub will bring together government, academia, and private sector industry partners to make Dayton a global leader in the research and development of digital transformation technologies. The project is also supported with a local match of at least $23 million and a private sector investment of up to $37 million.
"The Miami Valley has always been a place where big ideas take flight, and the unprecedented collaboration that will happen under the umbrella of the onMain Innovation Hub will lead to digital technologies that will impact lives across the world," said Governor DeWine in an August 2024 announcement. "This new collaboration will be transformative for this region, leading to more investments, more jobs, and more of the world's most innovative thinkers calling Dayton home."
📸 Ohio Department of Development
The Think Dayton building will house a center called the Digital Wing, which onMain says is “committed to providing a platform for government, industry, and academia to converge, collaborate, brainstorm, educate, and cooperate to advance digital transformation initiatives, particularly in support of the United States Air Force.”
Phase I of the onMain project also includes a planned residential building and stabilization of the historic Roundhouse, which has been completed.
Future vision for the former fairgrounds site, with landmarks like the Great Miami River, Roundhouse and Stewart and Main Streets 📸 onMain
Other key partners supporting the onMain Innovation Hub include Wright-Patterson Air Force Base, the University of Dayton Research Institute, the City of Dayton, Montgomery County, JobsOhio, and the Dayton Development Coalition.
By 2031, partners anticipate that the work of the hub will lead to 2,000 new jobs, more than $39 million in additional state and local income tax revenue, and $500 million in new research dollars.
The Roundhouse
One of the key elements of the onMain project is refurbishing the Roundhouse, an important historical landmark in Dayton dating back to 1874 and a memorable reminder of the former fairgrounds.
onMain says the Roundhouse will serve as a physical reminder of the site’s history and a living example of its creative, welcoming future. A plaza along Main Street will provide the grand entrance to onMain, leading to the Roundhouse. The area around the Roundhouse will provide flexible space for daily use as well as the ability to host both large and small community events.
Rendering of onMain development with Main Street entryway to the Roundhouse 📸 onMain
The Roundhouse is one of the few remaining of its kind in Ohio and the only original building retained on the site. Federal funding supported work on the Roundhouse in 2025. Repairs included repairing charred rafters and studs from a 1950s fire, reinforcing columns damaged by termites, replacing and painting exterior wood sigin and replacing windows. onMain says it is committed to exploring reuse strategies for the Roundhouse given its historic designation and prominence on the site. The site plan for onMain showcases the Roundhouse by having all roads lead to it.
An announcement by the University of Dayton says the Think Dayton building will be constructed and completed along with two new community spaces, with a projected opening in 2027.
© 2026 Twin Creek Times
