One building that always gets mentioned when it comes to Roman concrete (not in this article though, so I felt compelled to add it) is the Pantheon (https://en.

One building that always gets mentioned when it comes to Roman concrete (not in this article though, so I felt compelled to add it) is the Pantheon (https://en.wikipedia.org/wiki/Pantheon,_Rome https://en.wikipedia.org/wiki/Pantheon,_Rome), which is only ~100 years younger than the tomb of Caecilia Metella and features the world's largest unreinforced concrete dome (43 m / 142 ft diameter).