 It is constructed of nineteen arches, but is almost entirely enclosed by buildings on both sides, exposing only the largest arch where the street crosses the Cowgate.Below deck level are many buildings and vaults, the latter are now something of a tourist attraction.Most of the buildings on the deck level have separate entrances (and sometimes entirely separate functions) at the level of the street passing below (the Cowgate) or parallel to the bridge (Niddry Street and Blair Street).