Garden floor vestibule - drain

It seems my garden floor vestibule (under front stoop) is always damp since there’s no drain there. Not sure if there ever was, but it seems to be a design flaw if rain can pour in (no overhang over the steps leading down into vestibule) — maybe there was an awning meant to go there originally? Anyways always damp and when we replaced brownstone walls in vestibule the damp walls came crumbling down. Would a proper drain help future deterioration (since I’m assuming landmarks wouldn’t approve a cut-out in side wall to help cross airflow there — has anyone found a drain to help keep area dry (and alleviate mosquitoes there). Is it worth the investment of 1-2K to install a proper drain – not a french drain?