In brief
The Roman beginning is a starting point, but the value of the historical center covers many periods.
Useful to know
The history of Lyon begins with the Roman founding in the 1st century BC. UNESCO views its long political, cultural and economic development as visible in urban fabric and buildings from different periods. Therefore, the object is not explained only by the Roman remains. [1]
In a city with a long history, the architectural question is how old structures continue to participate in later life. Street, square and building can carry different time layers. Their general environment is more informative than an attempt to put everything in one style.
A practical approach when considering is to mark the period of the particular object and its relationship to the surrounding spaces. It's an observation exercise, not a ready-made date by appearance. Historical continuity does not mean that every building has been preserved unchanged since the city was founded.
Sources
For further detail and to check the information: