Conservators treat artworks at Lunder Conservation Center in Washington

A conservator treats an artwork at the Lunder Conservation Center of the Smithsonian American Art Museum in Washington D.C., the United States, on July 18, 2018. The Lunder Conservation Center allows the public behind-the-scenes views of essential preservation work. Visitors are able to see firsthand all the techniques that conservators use to examine, treat and preserve artworks. (Xinhua/Liu Jie)