Historically, Denver was the Queen City of the Plains, and Wednesday its centerpiece park became a jewel in the nation’s crown.

Denver’s Civic Center park has been designated a National Historic Landmark by the U.S. Department of Interior, the first such designee in Denver and one of three sites in Colorado to join the list this year.

The extension of the 64-mile extension of the Denver & Rio Grande Railroad through the San Juan Mountains and Big Spring Creek in Saguache County also joined the list.

“Each of these landmarks represents another thread in the great tapestry of our national park system that tells the story of our beautiful land, our diverse culture and our nation’s rich heritage,” U.S. Interior Secretary Ken Salazar, a former U.S. senator from Colorado, said in statement.

The downtown park becomes the first Denver site among 22 other national landmarks in Colorado that have been designated since the landmarks program began in 1935.

The 27 new entries join 2,527 national historic landmarks and 592 national natural landmark sites.

Sites are chosen based on for their ” exceptional value or quality in illustrating or interpreting the heritage of the United States,” associated with a turning point in American history

Denver Civic Center park is one of Denver’s most beautiful and, yes, historic locations, hosting presidents, protestors and festivals since 1886 in the space between the state, city an county buildings downtown. After he was elected in 1904, Mayor Robert Speer used the grounds as a focal point for his “City Beautiful” efforts, an urban planning trend in major cities at the beginning of the 20th century.

Only a handful of such parks were completed, and Denver’s downtown gathering place remains a glorious example of the City Beautiful movement’s intent, to deliver “beautification and monumental grandeur in cities to create moral and civic virtue among urban populations,” according to the Park Service

The San Juan Extension in Conejos and Archuleta counties, iwas part the original 1,000-mile Denver & Rio Grande Railroad network and was named a landmark because it represents “the country’s longest and most complete representation of late 19th- and early 20th-century railroading, and the best surviving example of the American railroad at its peak of national influence, roughly 1870 to 1930,” the National Park Service stated.

Big Spring Creek — located just beyond western edge of Great Sand Dunes National Park, northeast of Alamosa — is a stream fed from an underwater aquifer. Along with its wetlands, it supports “a diversity of rare species and plant communities in an otherwise arid landscape,” according to the Department of Interior.

Joey Bunch: 303-954-1174, jbunch@denverpost.com or twitter.com/joeybunch