London Mithraeum & Londinium

The Bloomberg building you're standing in front of right now is home to one of London's most extraordinary secrets: the London Mithraeum, a Roman temple buried beneath the city for centuries. But to understand why that temple is here, you first need to know the city it was built in.

Around the year 43, Roman forces arrived on the banks of the Thames and founded Londinium, a trading post built to move goods and people across their growing empire. It was practical, ambitious, and relentlessly busy. Within decades, it became the most important city in Roman Britain, filled with forums, bathhouses, and an amphitheater where thousands gathered.

But Londinium had a brutal early chapter. About a decade after its founding, Boudicca, queen of the Iceni tribe from what is now East Anglia, led a fierce uprising and burned the city nearly to the ground. The Romans rebuilt it stronger, and the city never looked back.

The Mithraeum, a temple dedicated to the mysterious cult of Mithras, was built here around the 3rd century, right in the heart of that thriving Roman city. When Roman forces finally withdrew in 407, they left behind streets and foundations that quietly shaped everything built on top of them, including, eventually, this very spot.

The Romans, it seems, had very good taste in real estate.