Yerevan sits on the lip of a deep volcanic gorge cut by the Hrazdan River, and walking down into it is one of the most surprising urban experiences in the city. From the top, the gorge is invisible; once you descend, the city falls away and you are in a quiet corridor of basalt cliffs, rope bridges, ruined Soviet-era industrial buildings, a few defunct outdoor swimming pools, and the Children's Railway terminus.
The Saryan Bridge, the Victory Bridge, and the dramatic Davtashen Bridge cross overhead. Several paths and stairways lead down from Kond, the Cascade district, and the Brandy Factory. Take an afternoon; bring water; it is not a polished tourist circuit but is genuinely worth doing.