NEWPORT, R.I. (WPRI) — A popular seaside mansion just underwent one of the most “extensive and complicated” restoration projects in its history, according to the Newport Preservation Society.

The Rosecliff has been closed for renovations since Jan. 2. 12 News got a firsthand look at the renovations Thursday ahead of its official reopening on Sept. 1.

Those renovations included replacing the 3,200-square-foot ballroom floor with an identical replica, adding a rubber “membrane” to the roof for better preservation and restoring the gardens, as well as repainting and cleaning throughout the building.

Newport Preservation Society CEO Trudy Coxe said this was a “longstanding, needed project” that cost $7.4 million. The restorations were funded by donations and ticket sales from mansion tours.

“It was a massive job,” she said, adding that the work was completed ahead of schedule and under budget. “We’re just finishing up now.”

Rosecliff has been the backdrop of various functions over the years, including exhibitions, weddings and company parties, according to Coxe.

“It’s a very important entertainment venue,” Coxe continued.

Coxe said the first public event at the newly-renovated mansion will be an exhibition that highlights the role Chinese-Americans played throughout the Gilded Age in Newport.

The mansion was first built back in 1902 and houses the city’s largest ballroom.

Ryan Welch contributed to this report.