The architects add that visitors enter, "... through an enclosed courtyard to the north, front of house we have created a welcoming and accessible building that is sensitive to the practical aspects of archive design, security, and environmental control and visitor routes. The courtyard provides off the street gathering spaces and, along with an internal flexible café, shop and welcome area can be opened up for special events."

Across the street, inside the Mount Pleasant Sorting Office is a small gift shop related to the Royal Mail but at the back of the shop a flight of stairs lead down to a new tourist attraction. 

For 76 years from 1927 until 2003 there was an underground railway that carried London's mail to and from major railway stations and sorting offices. Driverless trains travelled through tunnels that were just 2.7 metres wide between 8 stations that were in larger spaces, all of this 70 feet below London. An estimated 4 million letters a day travelled on this railway. In 2003 the dramatic decline in the number of pieces of mail being sent and the consolidation of sorting into fewer centres made the system uneconomical and it closed. 14 years later a portion of the railway has reopened using special adapted trains to carry people instead of letters.  The journey begins in a large station area below the sorting office.

Along the way the train stops at abandoned stations where the Mail Rail story is presented via an audio-visual presentation using the station walls as a screen.

At the conclusion of the journey visitors can browse through a small exhibition of equipment used by Mail Rail to transport the post around the country and then across London underground.