|The Fourth Avenue Historic District (Boundary Increase and Additional Documentation) is significant under NRHP Criterion A for its association with economics and commerce in Pittsburgh and under NRHP Criterion C as a cohesive concentration of buildings reflecting late nineteenth and early twentieth century architectural styles. The 1985 nomination for the Fourth Avenue Historic District characterizes the area as the historic core of Pittsburgh's downtown financial district. .. [which] ... was one of the nation's most important turn-of-the-century financial markets (Aurand 1985:6). The earlier nomination did not, however, capture the true scope and scale of commerce in the district. It briefly described office buildings, investment properties, and speculative building ventures, though they were emphasized less than their bank building counterparts. This amendment seeks to explain how the boundary increase is in keeping with the previously-listed district's economic and architectural significance. It also seeks to expand and clarify the earlier nomination's discussion of commercial significance to focus on all commerce in the district, not just finance. The buildings in the boundary increase area reflect this commercial significance with five properties that were acquired for banking offices, a speculative building for investment brokers, and a variety of offices, stores, and restaurants that served the local financial, business, and retail communities during the period of significance. The architectural significance of the district is demonstrated by the architectural richness of the predominantly Classical Revival buildings that were built in the boundary increase area within the Period of Significance. The period of significance (1871 to 1934) for the listed district and the boundary increase area was established in the original nomination and begins in 1871 with the completion of the initial building phase of the Dollar Savings Bank Building, which is the oldest extant building in the combined district. It ends in 1934, fifty years before the preparation of the original nomination. This range is appropriate for the boundary increase area as well, because all of the extant significant historical development in the increase area dates to this time period.