Site of the first schoolhouse (1808) in Buffalo which was burned by the British in 1813, this flatiron-shaped lot was a great challenge for architects Green and Wicks. The Dun Building, built between 1894-95 and named for its chief tenant R.G. Dun and Company - an internationally-known credit informational service, was Buffalo's first steel-framed "skyscraper." Ornate circular windows and high arches are part of the building's east facade. The arches, which give an open look and enhance the "skyscrapper" image, are also prominent features of other Green and Wicks buildings including the Buffalo Savings Bank (see 13-A) and the earlier Bank of Buffalo building at Main and Seneca Streets, now gone.

Robert G. Dun had joined the Mercantile Agency of New York City in 1850 and was soon a partner with his brother-in-law and later Dun became sole owner. The Mercantile Agency then was operated as the R.G. Dun Company and has had a presence in Buffalo since 1866. The Buffalo branch made its home in the Dun Building for 40 years. The popularity of Dun's credit rating reports led to the acquisition of a printing plant to produce a weekly report on business conditions and the company maintained branch offices in France and Germany as well. R.G. Dun was a pioneer in the use of the typewriter and every branch office had trained operators at the keyboard. In 1933, The R.G. Dun Company and Dun's Mercantile Agency absorbed the rival firm of The Bradstreet Company which was founded in 1849 by John M. Bradstreet and became known as Dun and Bradstreet.

The Dun Building, along with Louis Sullivan's Guaranty Building, Richard Upjohn's St. Paul's Episcopal Church and Daniel Burnham's Ellicott Square Building, is included in the Joseph Ellicott historic preservation district. Just to the northeast of the Dun Building on a site now occupied by the old M&T Trust Company building was the famous Weed Block, the Erie Street side of which included the apartment and law office of Grover Cleveland. Cleveland's phenomenal rise from mayor of Buffalo in 1882 to his election to the United States presidency in 1884, with a year as governor of New York State tucked in between, remains one of the quintessential political success stories in the annals of this country.