The Ludus Magnus, also known as the Great Gladiatorial Training School, was the largest of the gladiatorial schools in Rome. It was built by the emperor Domitian in the late first century C.E., alongside other building projects undertaken by him such as three other gladiatorial schools across the Roman Empire.
The training school is situated directly east of the Colosseum in the valley between the Esquiline and the Caelian hills, an area already occupied by Republican and Augustan structures. While there are remains that are visible today, they belong to a reconstruction that took place under the emperor Trajan where the Ludus plane was raised by about 1.5 metres.
Wikipedia https://en.wikipedia.org/wiki/Ludus_Magnus
Address 26 Via di San Giovanni in Laterano, Roma 00184, Italy
Coordinates 41°53'24.461" N 12°29'41.953" E