From the Pittsburgh and Allegheny Blue Book, 1899-1900. The Liberty Market was brand new when this ad ran. It failed as a retail market, but soon began a long association with the automobile industry that left it with the name Motor Square Garden. In 1988 it was redeveloped as a shopping arcade; once again, it failed as a retail space, and now it is known to most Pittsburghers as the headquarters of the local AAA affiliate. The building, currently having some restoration work done, looks almost exactly the same now as it did in 1900.
For those who wish to appreciate the details of the carriage trade lining up in front of the building, old Pa Pitt has provided an enlargement of the picture from the advertisement (click on it to make it very much bigger).