Zaragoza, or "Caesaraugusta" as it was known in Roman times, was the only Roman city that was named after it's founder, Caesar Augustus. This colony was also lucky enough to be exempt from paying taxes. During the first and second centuries, and at the height of its glory, many important public buildings were constructed here. Evidence of these structures still exists today in Zaragoza. A great way to see them all is to follow the "Caesaraugusta Route" or Roman route. Start off in Plaza de la Seo, in the old historic center, at the Caesaraugusta Forum Museum. Get a map there, and the rest of the route will be marked out for you. Here's a list of the four museums that are on that route, as well as some other Roman architecture worth checking out.
The Caesaraugusta Forum Museum
Plaza de la Seo, 2
The Caesaraugusta Public Baths Museum
San Juan y San Pedro street, 3-7
The Caesaraugusta Theatre Museum
San Jorge street, 12
The Caesarugusta River Port Museum
San Bruno Square, 8
The Crypt of Santa Engracia - Iglesia de Santa Engracia
Castellano street
The Roman walls of Caesaraugusta
César Augusto Avenue, at the end of Plaza Pilar