|Allegheny Commons is significant under National Register Criterion A in the area of Community Planning and Development and under Criterion C in the area of Landscape Architecture. With a period of significance extending from 1868 to 1967, Allegheny Commons is the oldest public park in Pittsburgh, the city's only formal urban park, and one of the first public parks developed west of the Allegheny Mountains. As such, Allegheny Commons embodies the distinctive characteristics of a sequence of movements in landscape design and urban park development from the 1860s to the 1960s, both as they emerged nationally and as they were adopted locally in Pittsburgh . Its character as a large park located in the center of a dense urban setting derives from the fact that the land was set aside for common grazing pasture when the once-independent town of Allegheny was surveyed in 1788. As Allegheny urbanized in the mid-191th century, the commons became derelict and disused, until its citizens pressed for it to be transformed into a public park. In this, Allegheny followed the lead of other cities such as New York, Boston, and Philadelphia, which were then developing elaborate public parks in which their citizens could seek despite from industrial pollution and urban overcrowding, and led the Pittsburgh region in public open space planning. The park was designed by the firm of Mitchell and Grant in 1867 utilizing a combination of formal, classical planning and picturesque landscape design which was ideally suited to its unique site . Over the ensuing. 100 years, Allegheny Commons retained many of the character-defining features of its original design, while accommodating an increasing emphasis on recreational activities in the early 20th century as well as elements of modern landscape design added pursuant to park planning campaigns in the 1930s and the 1960s.