This save game has a sky base built on top of the town of sanctuary
and has a five story high building, there is also two battle arenas in the town below and on top.

Required mods:
Settlement Supplies Expanded (SSEx):
http://www.nexusmods.com/fallout4/mods/1145/
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Settlements Expanded:
http://www.nexusmods.com/fallout4/mods/1062/?