The Marvelous Archdiocese of Baltimore Website

They simply don't make it any easier than this. If you go here, you'll find the "Parish" page. Note that the Parishes are organized alphabetically, by county (using a map) and by Vicariate (Archbishop O'Brien has several Auxiliary Bishops each of whom has an area of jurisdiction).

Below this, one can search for a Mass by "time and day." Put in the day and select the time and a Mass is found for you here. Note that one can search for Confession by time and day here. Here is a list of the Shrines, Grottos and also the Parishes of the Byzantine Rite. And for those looking for a Mass by language, for those who are hearing impaired and so on, go here.

Hat tip! It just doesn't get any easier than that!