The so-called ludus was on a scale to rival the famous ludus magnus, the gladiatorial school behind the Colosseum in Rome.
The remains at Carnuntum were mapped using sophisticated aerial surveys and ground-penetrating radar.
The archaeologists published their findings in the journal Antiquity.
Carnuntum was the capital of Upper Pannonia in Roman times and a major trading centre for amber.
Excavations in the late 19th and early 20th Centuries revealed many elements of the ancient settlement, including a legionary fortress and the civilian town.
It contains the ruins of amphitheatres, Roman baths and the remains of a monumental arch known as Heidentor.
The ludus was detected only in 2011, in an area to the south of the town, where little is visible on the surface.
According to this newly published survey, the school was complete with individual cells for the gladiators and a circular training arena.
Although about 100 ludi are thought to have existed in the Roman Empire, almost all have been destroyed or built over.
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