The remains of an ancient basilica that would have formed the heart of Roman London have been uncovered during building work in the center of the British capital.

Experts are surprised at how much of the basilica, or town hall, survived. The ancient building was part of Roman London’s political and commercial center.

The 2,000-year-old basilica was “once the beating heart of Roman London,” the Museum of London Archaeology said.

In the basement of an office building in London’s financial district, the ruins of an ancient Roman basilica were found buried beneath old filing cabinets and concrete floors. Archaeologists are calling it one of the most exciting recent discoveries in the British capital.