The block of Prospect Place between Flatbush and 6th Avenue is about to look a whole lot different. After the owner of 96 Prospect Place sold the adjacent 20-by-100-foot lot at 94 Prospect Place for $550,000 last summer, the new owner has begun work on what will be a new four-story house. The site falls outside of the Park Slope Historic District so the design is anybody’s guess. GMAP P*Shark DOB