The resounding crash of a door slamming resonates through the stately entrance of the Bank of England, flanked by grand columns.

Adorning the floors and walls are magnificent mosaics and sculptures illustrating lions, golden treasures, lightning bolts, and deities from ancient Rome.

“When this building was constructed, it was intended to function as an active bank. People flowed in and out all day long,” shares Jenni Adam, curator of the Bank of England Museum.

“And upon entry, visitors were immediately met with a palpable sense of magnificence, along with numerous messages about the significance of this location.”

A century ago, renovation work commenced on the Bank of England, which had begun as a townhouse in the 1700s and gradually expanded over the years.

To commemorate this centennial milestone, a new exhibit has been launched at the bank’s museum, exploring the treasures contained within one of the UK’s most secure establishments.

Leading up to its inauguration, the BBC was granted a rare glimpse inside the bank, where critical financial decisions are made and where approximately 400,000 gold bars are stored in the vaults below.

The bank was initially established under a Royal Charter in 1694 with the mission to manage the national debt and foster financial stability in Britain, according to Ms. Adam.

It experienced tremendous success, relocating to its current site on Threadneedle Street by 1734, gradually expanding and absorbing the surrounding area to create a three-and-a-half-acre (14,000 sq m) complex surrounded by a windowless wall.

Numerous distinguished architects, including Sir John Soane in the 1800s, contributed to the bank’s design, with his work regarded as one of the gems of the City.

However, by the early 20th century, Soane’s illustrious creation was deemed inadequate for the demands placed upon it.

“By the First World War, the staff count had surged from about 1,200 in 1914 to approximately 4,000 by 1918, revealing significant capacity issues,” Ms. Adam notes.

“The bank was successfully managing an expensive national debt among various challenges, leading to the decision to demolish and rebuild.”

Despite attempts to preserve much of its historic essence, the 14-year endeavor faced controversy, with one architecture specialist denouncing the demolition as “the greatest architectural crime to befall London in the 20th Century.”

Nevertheless, upon its completion in 1939, the undertaking, led by chief architect Sir Herbert Baker, ended up costing £5 million – equivalent to nearly £285 million today – with no costs spared in creating the nation’s central bank.

Signs of such opulence are visible throughout a structure that rises seven stories above ground and three below.

On the ground level, mosaics by the esteemed Russian artist Boris Anrep adorn a labyrinth of domed grey and black corridors, accompanied by figures and sculptures integrated throughout the furnishings.

Golden lions, representing security, are scattered throughout the space, from custom lighting to staircase banisters, while even the door handles showcase miniatures of Mercury, the Roman messenger god associated with commerce and finance.

“There’s an exquisite fusion of the modern and the ancient here. It gives the impression that even though this building is relatively new, it has a timeless presence,” Ms. Adam elaborates.

“It embodies a rich legacy and heritage. You can rely on it; it’s designed to last.”

Evidence of even earlier history is visible at the base of a spiraling staircase, where a Roman mosaic unearthed in the 1930s is proudly displayed.

Hidden off one corridor are grand banking halls inspired by Soane’s original designs, where the occasional sounds of thuds and clinks serve as reminders of the building’s operational nature.

Continuing up another flight of stairs, the environment shifts to one of regal elegance.

On the first-floor anteroom, red and gold silk lines the walls, embellished with centuries-old artworks and an ornately designed fireplace adjacent to a grand floor-to-ceiling window.

A set of imposing wooden double doors opens into an opulent pale blue octagonal chamber, where a portrait of a former governor watches over a reproduction of a room designed in the 1780s.

Without the microphones encircling a curved table and two television screens, few would suspect this space is where the bank’s monetary policy committee convenes monthly to make decisions that affect millions.

“This is currently where the committee meets to determine interest rates as part of the bank’s responsibility to control inflation,” Ms. Adam explains.

“The presence of the double doors ensures that no one can overhear these critical discussions pertaining to the markets.”

The atmosphere of an illustrious historical building, complemented by elements of modernity, continues throughout the floors, with many stone features—the fireplaces and columns from the previous structure—salvaged and reused by Baker.

Beyond another set of double doors lies the courtroom, where a branded lectern stands before an 18th-century fireplace under an exquisite green ceiling, with walls adorned in gold.

Silhouettes of monarchs throughout the bank’s history adorn the room, while gilded griffins stand guard over stacks of gold flanking the doorways.

A weather vane swings gently on one wall, invoking memories of a time when London’s port was nearly at the bank’s doorstep and a vital aspect of the city’s economy.

“The space is filled with symbols of finance and wealth… and gold flecks as far as the eye can see,” Ms. Adam remarks.

Due to stringent security measures, tours of the premises are exceedingly rare. The only glimpses of gold available are the two bars showcased in the museum that belong to the bank itself.

This is why Ms. Adam expresses her excitement to host an exhibition aimed at “revealing the architecture” and giving visitors insight into what lies within.

“I’ve been part of the bank for 15 years, and coming here every day makes it feel ordinary,” she reflects.

“Yet now and then, I wander around and think, ‘This is truly magnificent’—there are just so many stories and intricate details to share.”