A redo at city hall/"urban revitalization." I know you could consider this to be 3 different "projects," but...
1) Demolish 1,2, and 3 Center Plaza, offsetting the lost office space with a high rise on the north end of that parcel, next to the current courthouse, which would be retrofitted into city hall offices. Establish a new plaza in front of the new city hall and office tower.
2) Fill in City Hall Plaza, redo/demo JFK, refurb current city hall with public/civic space and retail on the lower floors and, as we've discussed elsewhere, BAC classrooms, lecture halls, and studios in the upper levels, and filling the rest with some leased office space
3) Fill in the state service center block with mid and high rises, possibly putting the lost square footage of federal offices and court space in there, or just regular mixed use residences/offices.
In total, probably $5 billion+