The lights go down. Total darkness. Total silence. Then voices, in the distance. Male voices – this strange and secretive place was for men only. Slowly, our eyes adjust and the lights come up and we can see two lines of columns and a sunken floor. The temple of Mithras is coming alive.

What remains of the building is located in the most unexpected place: at the bottom of a flight of steps under a massive, modern London office block owned by Bloomberg. This is pretty much the heart of the City of London and the area is functional and busy rather than beautiful and mysterious and yet here we are, underground, in the dark, close to the mysteries of Mithras.

The temple was first uncovered in 1954 during excavations carried out following the Blitz and for many years remained neglected and out in the open by the side of a busy road. Then in 2010, Bloomberg bought the site and created a new home for the temple under their HQ and this bunker museum was the remarkable result.

The voices of the men, heard through the gloom, come courtesy of a sound and light show which introduces the temple to visitors. What do we know about it? It was one of thousands that existed around the first to fourth centuries AD built in praise of Mithras, a god who legend says was born from a stone and was praised by many in Rome and its empire.

Beyond that, not much is known about the cult because, as Christianity rose, Mithraism faded and its records are lost. One theory, based on the ruins that remain, is that the cult was a men-only club that was masonic in nature – there were complex levels of initiation, possibly even a secret handshake, and the followers met in temples like this one to perform their rituals.

Visiting the museum now, more than 2000 years after it was built, is an extraordinary experience (and free, which is rare in London). Bloomberg have done a superb job in creating an atmospheric home for it and for visitors keen to explore a more unusual side of the city, it’s the ideal highlight of a visit that’s a little different – an experience that seeks to go beneath and behind and between the streets of the old City.

A good base for such a visit is the Strand Palace, a large, handsome and comfortable hotel on the great thoroughfare from Westminster to Fleet Street. Some of the more surprising and curious places to visit in London, such as the temple, are all within walking distance. Turn right as you leave the hotel and you’re at Trafalgar Square.

Turn left and you can dive into another ancient, mysterious and haunted city. Heading down the Strand, I pass all the statues you’d expect – monuments to kings, dukes, politicians and soldiers – but even in the 19th century some people, like the painter GF Watts, thought there were others who should be recognised too. Watts’s plan was for every city to have memorials to ordinary people but when he failed to win the support of government or town planners, he decided to do it himself.

The result is a moving memorial near St Paul’s Cathedral in Postman’s Park, one of the less well known of London’s parks, and the smallest. It would be easy to miss this place if you didn’t know it was here and the effect is striking: one minute, people, cars, noise; the next, a beautiful little pocket of green.

This is where locals-in-the-know come for a quiet rest. A solitary pigeon is standing on the lawn – perhaps this is also where even pigeons come to be alone.

The memorial that Watts created is against a wall at the back of the park and it’s a beautiful thing. Arranged in rows are plaques remembering people who lost their lives trying to save others.

People like 19-year-old Amelia Kennedy, who died in 1871 while trying to save her sister from a burning house. And David Selves, who in 1886 “supported his drowning playfellow and sank with him clasped in his arms”. These people weren’t famous but their memorials are just as rewarding, if not more so, than the statues of the great men and women in the streets nearby.

I have to say: I’m liking this side of London, the slightly more unusual version to be found off the main thoroughfares of tourism. Near the park, on the edge of the City, is the boundary of the old Roman settlement and it’s a place where the veil over history is thin: violent history, ghostly history, ancient history.

I walk up to Smithfield, the only meat market that has continued on the same site since the Middle Ages, and on to the memorial to William Wallace near the place where he was executed. Beyond is St Bart’s Hospital where Holmes and Watson met for the first time. This happens in London: fiction and fact inter-mingle. These are also the streets where Fagin roamed and where Pip arrived with his expectations.

The streets here are also home to the city’s A-list celebrity ghosts, including one who became the most famous in London. I walk up to the place where she roamed: an unprepossessing street near the Old Bailey. In a gift to fans of double entendre, the street is called Cock Lane and the ghost was called Fanny and in the late 18th century, she is said to have produced frightening scratching noises “like a cat fossicking a cane chair”. It turned out, sadly, that it was a bit of a drunken joke gone wrong but it’s interesting to see the place (and listen). And there’s more history, because there always is: this street is the furthest point that the Great Fire reached.

But it’s time to take a brief rest from history so I stop in to the Viaduct Tavern, which turns out to be full of history as well (of course it does). It has a ghost of its own, it’s built on the site of an old prison, and you can see its history too in the faces of the old guys sipping their drinks. It’s the perfect place really to finish off my morning looking for clues from the past. Yesterday’s streets become today’s pub and I order a pint and some crisps and enjoy the present.

 

Rooms at the Strand Palace start at £102, doubles start from £190. Afternoon tea in the Haxells Tearoom includes finger sandwiches such as Scottish smoked salmon with black pepper. Sweet treats on offer include Matcha tea; raspberry Battenberg; plain or fruit scones with clotted cream and strawberry jam. 

Find out more at strandpalacehotel.co.uk