Philip G. Freelon, an architect whose long list of credits includes museums and other cultural institutions devoted to the black experience, among them the National Museum of African American History and Culture on the Mall in Washington, died on Tuesday at his home in Durham, N.C. He was 66.

The cause was amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, his friend and spokesman, Michael J. Reilly, said.

In addition to the Washington museum and other notable buildings, Mr. Freelon designed or helped design the National Center for Civil and Human Rights in Atlanta, the Museum of the African Diaspora in San Francisco and the Mississippi Civil Rights Museum in Jackson.

The architecture firm Perkins & Will, with which his own firm, the Freelon Group, merged several years ago, described Mr. Freelon in a statement as “arguably the most significant African-American architect in recent history.”