A project which reveals Birmingham’s hidden architectural landmarks begins this summer, with a series of walking tours.

BBC Midlands Today’s Satnam Rana met two of the people behind the Hidden Spaces project, Jack Tasker from Associated Architects, and Ben Waddington from tour company Still Walking.

Piccadilly Arcade and Centenary Square are accessible to all – and to spot their key features, a knowledgeable guide is all that is needed.

However tunnels linking the Mailbox to New Street Station, and the inside of the Freemasons’ Hall on Severn Street, are just two of the places that are normally impossible to visit. So what could you see?

Mailbox tunnel

Beneath the surface of the Mailbox, an angular red building which now houses exclusive shops and restaurants, most of the original fabric of the 1970s letter and parcel sorting office once there still exists – including a tunnel which does not appear on any maps.

It links up with New Street Station, as it once conveyed mail to and from the trains.

Some of the other remaining mail tunnels, which sit below the platforms of New Street Station, are to be reopened as staff tunnels as part of the station’s renovation, allowing fast access from one side of the new station to the other.

Birmingham Municipal Bank

The Grade II-listed building was completed in 1933 to house the newly founded civic institution.

The Birmingham Municipal Bank was set up for the ordinary worker to make small savings, and to raise funds for the First World War effort. The bank later became Trustee Savings Bank, or TSB.

Since being abandoned as a bank the building has been used as a space for arts and film.

Curzon Street

The rail station at Curzon Street was originally known as Birmingham Station before New Street was constructed, and was the terminus of the first railway line to link London to Birmingham.

The surviving building is Grade I listed, but empty and unused with broken windows, although original features such as fireplaces and light fixings remain.

A mummified cat was discovered under the floorboards during renovation works in the 1980s.

It is thought that the cat was buried alive before the building was completed in 1838, as a Victorian tradition intended to bring good luck to the future building occupants.

Severn Street Masonic Hall

Sitting in the shadow of the Mailbox, the Severn Street Masonic Hall is a modest Victorian building, originally built in 1809 as a synagogue for Birmingham’s Jewish community.

A society shrouded in secrecy, only Freemasons are admitted to see the chequerboard floor, which represents the light and darkness of life, and the ceiling decorated to resemble the night sky.

The Grand Hotel

The Grand Hotel on Colmore Row was first designed by Thomson Plevins and was constructed between 1877 and 1879.

King George VI, the Duke of Windsor, Winston Churchill, Neville Chamberlain, and Charlie Chaplin are just some of the people who either stayed at or attended functions at the hotel.

From the early 1970s it was leased to a number of hotel chains which each in turn attempted to modernise the building – but underneath, the Victorian embellishments remain.

Birmingham Museum and Art Gallery warehouse

The flamboyant Birmingham Museum and Art Gallery opened in 1879 as an extension to the renaissance-inspired Council House by the same architect, Yeoville Thomason.

But in an industrial warehouse in Nechells, the Birmingham Museums Trust keeps more than 500,000 objects, storing the hundreds of thousands of items that move between the Trust’s seven sites.

There are large areas within the building which are inaccessible to the public, where specialist equipment and machinery is used in carrying out conservation work.