An office building from the 1930s in the heart of London was about to be demolished and redeveloped by its owners — until archaeologists unearthed remnants of the city’s first Roman basilica in the basement.

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.

While exploring the site of a 32-story planned skyscraper in London, archaeologists unearthed the ruins of a nearly 2,000-year-old Roman basilica.

The plan was to demolish the old office building at 85 Gracechurch Street in the heart of London’s financial district and construct a new 32-story tower in its place. But as demolition began, archaeologists made a staggering discovery in the site’s foundation: remarkably intact ruins of London’s first public building,