(Photo: AP)

The National Park Service is assessing a series of cracks that have begun to appear in the World War II Memorial as Washington, DC, prepares for an increase in visitors over Memorial Day weekend.

The Park Service says in a statement Friday that a large crack is visible on the memorial’s Atlantic arch and a smaller crack is visible on the District of Columbia column. A structural assessment is underway, and a timeline for repairs is being developed.

The Park Service announced that the memorial “remains structurally sound” and there is no threat to the safety of visitors.

Opened in 2004, the memorial consists of 56 pillars and a pair of arches surrounding a central fountain. Last year, it had about 4.6 million visitors.