Kansas City, Mo. ? The secretary of the interior Thursday designated the Liberty Memorial Monument a National Historic Landmark.

The World War I memorial, dedicated in 1921 and built between 1923 and 1938, covers almost 50 acres on the crest of a hill near Kansas City’s Union Station and includes the monument, museum building and other structures.

“The Liberty Memorial in Kansas City is one of the compelling monuments constructed in honor of those who gave their lives in World War I,” Interior Secretary Dirk Kempthorne said in a written statement.

About 2,500 sites have the designation of National Historic Landmark.