PORTLAND – “Becoming a Nation: Americana from the Diplomatic Reception Rooms, U.S. Department of State” is on view at the Portland Museum of Art through Jan. 2.

The exhibition features 170 objects from the diplomatic reception rooms, one of the nation’s least-known cultural treasures, which constitutes an extraordinary collection of Americana, according to the museum.

The exhibition, curated by Dr. Jonathan Fairbanks, presents some fine examples of American paintings, sculpture, decorative arts and furniture from the golden age of American decorative and fine arts, approximately 1750-1825.

It includes a great Philadelphia chest attributed to Joseph Deleveau and an exquisite settee by Duncan Phyfe; paintings by J.S. Copley, C.W. Peale, Gilbert Stuart and Thomas Sully; silver by Paul Revere II and John Le Tellier; and porcelain belonging to George Washington and elegant pewter. All these objects highlight America’s achievement in the arts in the Colonial and Federal periods, according to the museum.

The early Americans who owned these works and the artisans who made them clearly had sophisticated aesthetics, a rational sense of function and high technical skills, the museum’s spokesman said.

Starting in the 1950s, the collection was assembled as part of a larger plan to transform a suite of box-like rooms into an elegant and distinctively American backdrop for affairs of state. The result, designed and assembled in only 30 years, is a series of graceful rooms for entertaining diplomats and foreign heads of state that is renowned for its beauty.