|Constructed between 1966 and 1970 as a vital part of the South Auditorium Urban Renewal District, the Halprin Open Space Sequence is nationally significant under Criterion C for Landscape Architecture. Specifically, it is a masterwork by transformative landscape architect Lawrence Halprin. This work is one of the largest, most complex, comprehensive and sophisticated expressions of Halprin 's concepts for public plazas. The work is also seminal in that it is the first full expression of concepts that he would later repeat in varying formats for the next four decades. As characterized by Kenneth Helphand, Knight Professor Emeritus of Landscape Architecture at the University of Oregon - The Portland Open Space Sequence. .. is an acknowledged masterpiece of modern design. Halprin is one of the great landscape architects of the twentieth century. His work helped revitalize the profession in the United States and was a model of design that was creative, innovative and addressed the urban condition. The Portland fountains are known worldwide ... It would not overstate the case to say that they have been a pilgrimage site for design professionals, for they changed the concept of the urban fountain and were the catalyst for a revivification of fountain and urban open space design.- The Halprin Open Space Sequence is also locally significant under Criterion A for Community Development. Halprin's plazas and promenades created a unique, vibrant, and people-pleasing setting. By so doing, it encouraged further private investment within the South Auditorium district and fostered expansion of urban renewal as a policy tool northward and westward. The success of the sequence also established a local expectation in urban plaza design, an expectation carried forward in places such as Pioneer Courthouse Square, Director Park , and Jamison Square. It further established the notion of a sequence of parks, carried forward today in the similarly orchestrated series of parks in the Pearl District.