Aula Palatina

Immense Roman audience hall built for Constantine, still standing intact

The Konstantinbasilika (Constantine's Basilica) is the largest surviving Roman building from antiquity that remains substantially intact. Built around AD 310 as the throne room of Emperor Constantine I — who governed the entire Roman Empire from Trier for a period — the hall is 67 metres long, 27 metres wide, and 30 metres high, with original Roman brick walls still reaching full height.

Today it functions as a Protestant church, but the space is so vast and austere that it reads primarily as a monument to Roman architecture. The enormous windows, added in the 17th and 19th centuries, fill the hall with light that would have been absent in Roman times — the original was richly decorated with marble and mosaics, none of which survive. Archaeological reconstructions of the original interior are displayed in the building.

It stands just beside the Electoral Palace, the 18th-century residence of the Prince-Electors of Trier — the contrast between the two buildings, separated by a small formal garden, is striking.

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A story
The Aula Palatina is one of the best-preserved Roman buildings in the world — and one of the most astonishing. When you stand inside its 67-metre nave (longer than a football pitch), it is difficult to believe the walls are 1700 years old. The building's survival is partly accidental: it was converted into a palace in the 13th century, then a church, and has been a Protestant church since 1856, which is why it was maintained rather than quarried for stone.