Off the top of my head there are two surface decent size surface parking lots within one block of the Penebscot [[the lot on the northeast and the lot on the northwest intersection of Larned/Shelby). Those seem large enough for a garage. Hell, there is even that little inlet by the salad place on Congress [[though that must be too small for garage).

Maybe this owner should spend a little more money purchasing lots to make his investments worthwhile before he decides to destroy our history.