This tunnel formerly carried a railway line under both Broughton Road and Rodney Street, and may be considered as a Northern counterpart to the Scotland Street Tunnel. The 1967 edition of the OS 1:1250 map depicts railway tracks as entering it from the North.
The tunnel was built as part of the original main route from Edinburgh (Canal Street Station) to the North via the ferry between the railway harbours at Granton and Burntisland. It was operated successively by the Edinburgh, Leith and Newhaven Railway, the Edinburgh, Leith and Granton Railway, and the Edinburgh, Perth and Dundee Railway, before being taken over (in 1862) by the North British Railway. The NBR constructed a replacement line via Abbeyhill, which was opened in 1868, but the tunnel remained in use until 1968 to serve a coal depot at Scotland Street.
The tunnel was reopened in 2009 as a bicycle and pedestrian route by the City of Edinburgh Council in association with SUSTRANS and the Scottish Government.
Part of the cycle and foot path following the route of the Edinburgh, Leith and Newhaven Railway, and one of a set of four caches I have placed along it. A wee mix of a traditional (this one), a couple of multi-caches (Bichrist This Tunnel Is Mingin' and Trinity Tunnel Trot) and a letterbox hybrid (REALLY SideTracked - Trinity Railway Station).
Coordinates are for the tunnel entrance and are a short distance from the cache.