I've been to lots of roman ruins but that place was a favorite because the setting is beautiful and peaceful, there was hardly anyone there, it was ridiculously accessible, and the mosaics and ruins (including and amphitheater) were just very cool.
That sounds like it was a great experience!
https://www.andalucia.com/cities/seville/italica.htm
Pretty cool place. The website says there are “signs on the road” so it sounds like it still might be an uncrowded place. Although in 2016 the show Game of Thrones used it for filming.