Tomorrow, Thursday May 18, 2017, is Art Museum Day here in the U.S.

Organized by the Association of Art Museum Directors, it’s an event in which participating museums open their doors for free and often feature events, tours and museum shop discounts.

Unlike the broader Museum Day, organized by the Smithsonian and generally held in September, this event has no requirement for advance tickets or limitations on the number of museums you can visit on the day.

This page devoted to Art Museum Day, though it may not be obvious at first, offers a list of participating museums, arranged by state.

The images above are of some of the participating museums here in the Philadelphia area: the Philadelphia Museum of Art; The Brandywine River Museum of Art, the Pennsylvania Academy of the Fine Arts Museum of American Art and the Barnes Foundation.