If you've read the title then you know I have a theory about The Avengers Mansion showing up in the MCU. It's just a theory so don't go hating or anything. Y'see the Avengers Mansion is a, well, mansion. It was owned by the Stark family and watched over by their butler Edwin Jarvis, after Tony Stark became Iron Man he didn't need it anymore so he gave it to the Avengers. The mansion is a place to think, plan, assemble, have parties etc. It's also the lab where Ant-Man and Tony Stark invented Ultron.
How could it end up in the MCU? Well for since The Avengers are expanding with additions of War Machine, The Vision, Scarlet Witch,Falcon and Ant-Man, I'm pretty sure the tower isn't big enough. And besides, they can't risk tje tower falling on top of people if another invasion happens. Specifically with the MCU expanding and with heroes like Daredevil, Punisher, Iron Fist, Captain Marvel joining the MCU and eventually become avengers, they'd need a bigger home and a certain building in Avengers Age of Ultron is the building I think would become The Avengers Mansion.
This building right here
Remember when Tony was fighting The Hulk using the Hulkbuster? And remember how he was finding a way to calm Hulk down and he scanned the building and tells J.A.R.V.I.S
How quickly can we buy this building?
And then he just slams Hulk down the building like...
Well that line, can either be a joke or a possibility, but my money's on possibility. What if Tony did buy that building and it makes sense, because Tony bought that building and doesn't know what to do with the land after he destroyed the building, he might as well build the Avengers Mansion.
That's my theory on the Avengers Mansion ending up in the MCU.