The Mailbox, with its bold red façade, alludes proudly to its Royal Mail heritage. In actual fact, beneath the surface, most of the original fabric of the 1970s letter and parcel sorting office still exists.
Up until the late 1960s the Royal Mail parcel and letter sorting offices were based in two buildings on Victoria Square, connected by a bridge spanning Hill Street, where they had been housed for almost 80 years.
In 1970, a new, purpose-built, sorting office was constructed on the site of a former railway goods yard, adjacent to canal wharfs of the Birmingham and Worcester canal.
Not only was it the largest building in Birmingham at the time, it was also the largest mechanised letters and parcels sorting office in the country.
Coincident to this, the House of Commons passed a bill allowing an underground connection to be made between the new sorting office and New Street station.
A 400m long tunnel was constructed beneath Severn Street, which extended the existing underground tunnels at the station that already connected to the Victorian sorting office on Victoria Square.
Upon completion, small electric trucks known as 'brutes' were able to pull cages full of mailbags straight off the trains, along the secure passageway, directly into the impenetrable structure of the sorting office.
From there a network of lifts, chutes and conveyor belts distributed the mail through the building.
It is rumoured that because the link was so secure, jewellers across the city would post their diamonds to themselves on a Friday evening, as it was cheaper than storing them in a vault over the weekend.
The tunnel does not appear on any maps, but it still exists; a gently curving cavern beneath the streets, containing nothing but the haunting sound of trains and platform announcements echoing in the distance.
The tunnel has remained beneath The Mailbox, a reminder of the building’s former use, but now redundant except for the occasional party, exhibition and even wedding.
Some of the other remaining mail tunnels, which sit below the platforms of New Street Station, are to be reopened as staff tunnels, allowing fast access from one side of the new station to the other.
The Royal Mail sorting office was moved to Aston in 1998, no longer dependant on the rail network. In 1999 the sorting office was bought by the ambitious developers Birmingham Mailbox Limited, who had the radical vision of turning the industrial building into a mixed-use destination.
The scheme for the building, designed by Associated Architects, involved carving a street right through the centre of the building.
This bold urban design move subsequently transformed the west-side of the city centre, creating a new connection to Brindleyplace. This was possible via the canal wharf at the rear of the building, which had been covered over and was unexpectedly discovered during the design process.
Following the extensive redevelopment the building reopened in 2001. At that time it was said to be the largest mixed-use conversion in the UK.
In 2011, the building was sold to Brockton Capital in a joint venture with Milligan and is currently undergoing renovation works, due to complete in spring 2015.
These works represent another new chapter for the site.