I’m assuming the city came first, and then the expressways? In Cairo, the government built dozens of haphazard flyovers to let through traffic on major streets avoid busy intersections – it basically created the same effect.
Interestingly, in Flushing, which is now New York’s largest Asian neighborhood, there’s similar street activity under the subway and railroad bridges – newsstands and concessionaires that look like they’ve been built into the bridge abutments.
The highways came later, but they’ve been integrated into the city pretty well, and they function almost as boulevards lined by large apartment buildings and hotels.
In Hong Kong there are a lot of flyovers built to facilitate traffic — in fact the two major roads in either direction of my apartment have them. They’re not too intrusive since they only have two lanes each and not too much traffic. Some of the busier flyovers (like the one that runs above Canal Street in Causeway Bay) are pretty noisy and polluted, though.