It seems quite a hazard for paedestrians,
I am guessing air vent to some secret treasure laden underground hideout or a tube to access for unblocking clogged waste water pipes?
Could there be a secret city below the pavement :?:
I could not believe my eyes when spotted the pipe for first time and still do not know what it is good for (maybe pouring a few litres of water in would reveal something ) and why people did not make the outlet coming from the wall for instance instead. Mhm, there are mysteries around the world...