CHARLESTON — Crews are now working seven days a week to finish the most expensive municipal project in Charleston’s 350-year history.

The Post and Courier of Charleston reports crews are at the site every day and work two shifts on weekdays on the $142 million Gaillard Center.

The performing arts center is replacing the aging Gaillard Municipal Auditorium which was built in 1968.

The new performance hall will be a key venue for the Spoleto Festival USA. The project also includes a ballroom, banquet space, outdoor gardens and city offices.

“It’s a big project and a complicated project,” Charleston Mayor Joseph P. Riley Jr. said.

He said the project is still on schedule to be completed by April. The 2015 Spoleto Festival USA opens the following month.

Dustin Clemens, the city’s director of capital projects, said that from the beginning it was known that the construction company, Skanska Trident, would at times have to work on weekends and include a second shift.

“The details of this building are extraordinary,” Clemens said. “They always knew it would take some extra work.”

Currently, more than 400 workers are at the site during the day with about 25 on the second shift. About 100 work on Saturdays and about 10 on Sundays. Most of the weekend work is on the interior.

Clemens said the seven-day-a-week schedule will likely continue through September.

Ground was broken nearly two years ago on the project which officials said is now more than half complete.