Structurally sound spot for long term placement of very heavy item – GreenBuildingAdvisor

Shout out to all those present who are either carpenters or structural engineers ! Thank u for your valuable contributions over the years to this forum ! Now heres a question that stumps me but surely will be easy for you all: Where is the best spot, inside a one story wood frame, single family house, to place (long term) a very heavy antique upright piano? For years ours sat in the middle of a room, parallel to the floor joists. Over time, this floor began to sag (although not drastically). The sagging is very slightly visible to naked eye when one looks down at floor from inside the room or stands in cellar & looks upwards. For structural integrity, would a better spot to store the piano have been: a) alomg an exterior wall; b) at an exterior corner; c) along any bearing wall (not necessarily exterior) ? Thank you