COLLINSVILLE, Ill. (AP) — Portions of the Cahokia Mounds State Historic Site in southern Illinois will close March 1 as work begins on a $5 million project.

The work, which includes replacing the roof, lighting and fire suppression and security systems, is expected to take about a year, said Superintendent Lori Belknap.

She said some of the work was last done in 1988.

The 2,200-acre site near Collinsville, about 12 miles east of St. Louis, contains remains of the most sophisticated prehistoric native civilization north of Mexico.

“When the Interpretive Center reopens, visitors will see many improvements including restoration of our theatre, along with upgrades and improvements to gallery elements, enhancing visitor experiences,” Belknap said.

During the project, there will be no public access to the main parking lot and surrounding area, but the Monks Mound parking lot and trails north of Collinsville Road will remain open.

The Cahokia Mounds Museum Society plans to host events outside the Interpretive Center and walking tours might resume in the spring.