Or Circus Moderatus? The famous one in Rome is 2,037 ft by 387 ft and there was for a while an even bigger one near the present central train station. The well preserved Circus of Maxentius on via Appia of Rome has a spina barrier alone of exactly 1000 Roman feet:
P.S. for those concerned about unprecedented tourist crowds in Rome, I have only ever seen at most a couple of visitors at this atmospheric site. One in a cluster of many undervisited sites.