In brief
The same location brings different city stories.
Useful to know
Carthage was founded in the ninth century BC and was destroyed by the Romans in 146 BC. Later, Roman Carthage developed on the remains of the Punic city. [1]
This sequence is key when reading the archaeological site near Tunisia. A Roman public building is not an automatic testimony to the device of the earlier Punic city. When you're looking at a reconstruction, check out which period it's restoring. The difference between the visible remains and the older layers helps not to create an imaginary unified city of elements separated by centuries.
Sources
For further detail and to check the information: