WATERVILLE — The Colby College Museum of Art, closed for a month as construction began on a $15 million expansion, reopened this week.

On display is an exhibition dedicated to the pavilion’s design and rotating highlights from its permanent collection.

The Alfond-Lunder Family Pavilion, a 26,000-square-foot addition, will include 10,000 feet of new exhibition space. The new space is expected to open in summer 2013, making Colby’s museum the largest in Maine.

Now, the museum is 28,000 square feet. The expansion will increase the total to 54,000 square feet, with 38,000 square feet of space used for art exhibition.

Its galleries reopened Tuesday, offering a glimpse at the construction work yet to come. The glass pavilion has been designed by Los Angeles-based Frederick Fisher and Partners and college officials say it’s needed to accommodate a growing collection and other programs.

Kelly Doran, the project manager and assistant director for capital planning and construction at Colby, said crews are working on interior demolition and expect to begin removing ledge by the end of the month. The contractor is Consigli Construction, of Portland.

“The building will start to rise in the spring, in March,” Doran said. “The design itself is certainly going to be unique for Maine in general. It’s distinct in that it’s different from the rest of our campus and will certainly signify that its a museum.”

The project is expected to include a sculpture terrace and a classroom for museum education and outreach. The addition’s top floor will house art department studios.

Now that the museum has reopened, visitors enter through a new, temporary entrance adjacent to the Paul J. Schupf Wing, beside Roberts parking lot.

The exhibit about the new addition, “Process and Place: Exploring the Design Evolution of the Alfond-Lunder Family Pavilion,” aims to explore “the contextual, collaborative, and place-envisioning process” that has led to the building design.

Also on display through Jan. 22 is “Rediscoveries 1: New Perspectives on the Permanent Collection,” which contains a variety of selections from the permanent collection aimed at illustrating the idea that a museum “is a platform for new ideas from diverse perspectives.” Also on display as an ongoing exhibition are paintings, drawings and prints by Alex Katz.

The Colby College Museum of Art is open Sunday from noon to 5 p.m., and Tuesday through Saturday, from 10 a.m. to 5 p.m. For more information, visit www.colby.edu/museum or call 859-5600.