Here, he discusses the renovations, and why the name change,
"Last time we saw Stark Tower, from The Avengers, it had gotten beat up a little bit thanks to Hulk and thanks to Loki and the Chituari, and Pepper and Tony were standing over a table looking at plans" he explained. "That's where we pulled out and all the letters had fallen away except the 'A' in Stark. So what they were doing was retro-fitting for The Avengers. And that's what we see in this next film.
S.H.I.E.L.D. is gone - for people who are following along. S.H.I.E.L.D. was disbanded and brought down at the end of The Winter Soldier because it turned out to not be the best organization ever. So Tony's bank-rolling The Avengers now. And he's bank-rolling their headquarters. So it's now Avengers Tower.
Tony designed it so in addition to a hanger for a brand-new Quinjet, laboratories, places where he can build and store his Iron Man suits, there are I believe two bars. Beautiful multiple space living rooms, which are perfect for parties and social gatherings. But it's a primary location in the film this time around."
The first Avengers: Age of Ultron footage contained a scene between Hulk and Tony Stark's Hulkbuster armor, though there is a debate about who is actually controlling this armor. Is it Ultron? Or is Hulk seriously out of control?
Kevin Feige discussed the scene in more detail, offering new insight into some of the sequel's cool gadgets.
"There are a lot of scenes that you should be getting excited about. That is certainly one of them. I think I said a long time ago when Joss [Whedon] first did his six-page or 10-page outline for Avengers there was a lot of work and the movie's adapted quite a bit since then, but there were like six or seven signature things just in that. I said 'Joss, even if we don't do anything else. Just do these seven things, that's enough for the movie. Now let's get to work and put it all together.' Those things are in the movie and are amazing, of which that sequence is one."