Sadly, Pontiac was a victim of 1960's urban renewal. A good 1/3 of the downtown was demolished, including most of its theater district. The Clinton River, which snaked through downtown, was straightened out and buried underground in pipes.
They looked at several proposals, including one from a young Pontiac native Alfred Taubman. Unfortunately, they chose the current design that bypasses downtown completely with what it now the Woodward Loop. Before 1960, everyone driving from Detroit to Flint had to drive through Pontiac. Now, nobody does.
I've seen a lot of references about the size of the buildings considering the size of the city. You have to remember, at its peak, Pontiac had 86,000 residents and was the largest city in Oakland County until Southfield passed it in the 1990s and larger than Ann Arbor until 1970. When most of the large buildings were built in the late 1920's, Pontiac had just experienced a 250% population growth in 10 years.
The below picture is from the 1930's. Compare it with the one below that is pretty current, and you can see how much Pontiac has lost. My dad remembered Pontiac as a place with no parking. Now it looks like it is mostly parking.