I'm sure they could break the limit if they wanted too, atleast in certain ares. Some planes do fly pretty low over downtown, so I don't know if they were going to build up, if they'd have to push further away from downtown. The river I'm pretty sure is the flight path guide, or w/e. So whatever is built would prob be further east than closer to the Merrimack. If there were to be a height limit in any part of the city, I think it should be on the West Side, St Marie's church dominates the area, and you can see it from any part of downtown or the West Side. If something were built above it or close, it would be very awkward I think. Are they still planning on the 30 story building in Portland? I do admit, that I would be disappointed if Manch lost it's tallest north of Boston title.