UK studio ScanLAB Projects have created digital 3D scans of the entire length of the Mail Rail.
The project records the Mail Rail's days as a working infrastructure, in unprecedented detail.
The scans are created by bouncing a laser off objects in its path, capturing minute details.
This aerial view of the Mail Rail under The Postal Museum -- seen from Farringdon Road -- shows the loop of the track where trains will soon be carrying curious visitors through a section of the tunnel.
The Mail Rail stretches across 23 miles of track underneath London.
In 2017, a section of the postal tunnel will be open to visitors as part of the new Postal Museum.