To my logic the idea was that it had to look like a hit, to lure the main target to Skyrim so by the stone head dropping on her it may be ruled a accident. And yes I know the game doesn't share that logic but its a roleplaying game, so I role play. I took my shot from the walkway with a glass arrow to the check then sneaked along the walk day, jumped down to a rooftop then down to the street before taking the hidden entrance to Solitude (inside that tower separating the districts) and only fast travelled once I was out of the city.