I suggest you start with the City of Worcester Assessor's Office web page. If you look at thr 2002 Property Assessments and enter the address you can get the MLB number and the Map-Book-Page reference. The site will also give you information about the date of construction and construction materials. With the Map-Book-Page number you can go to the Registry of Deeds at the Courthouse and look up previous owners. Of course, if it is in one of the historical neighborhoods (Crown Hill, Massachusetts Ave., etc.) you may have luck at the Worcester Historical Society.