These are the remains of the amphitheatre in Padua, there’s not much surviving other than this external wall but at least it gives an impression of the scale although quite a lot of imagination is needed to picture what this might have once looked like.
The amphitheatre survived in some form until the Middle Ages, when they promptly demolished it as they wanted the marble. That left them with a big pit and some lovely shiny new buildings at least.
When the Romans built this amphitheatre to entertain the locals, the city was known as Patavium. The construction started in around 70 AD and this entertainment centre was used by gladiators to prance about in, and often dying for their art. It was of an elliptical shape and would have been able to hold several thousand spectators.
I asked AI to create an image of what the amphitheatre might have looked like and this doesn’t feel unreasonable, although I’m not sure that it was quite as substantial as this. What’s left can be seen in Giardini dell’Arena, an area which was purchased by the Scrovegni family in the fourteenth century and they built quite a decadent chapel on the site.
Unfortunately, there’s not much Roman left in Padua, as the remains of this building and some bridge foundations are all that are left in terms of Roman monuments.