This is a resin detail parts set for use with military vehicle kits.
From the Airfix website:
These city steps enable a huge scope of modelling opportunities to be created, and these steps can be found right across Europe. Great to be used in wargaming scenarios, too .1:76, 1:72 and larger scale figures can be used with these.
When completed, this model measures about 155mm long, 140mm wide and 95mm tall.