In the Gadget/Vehicle/Weapon category I'm proud to select... the S.H.I.E.L.D Helicarrier.
(That's it above Cap's head)
The Helicarrier is an aircraft that is constantly in the air. It is huge enough to hold an aircraft carrier. It is the mobile headquarters of SHIELD-and is extremely protected. The Helicarrier has held an entire squadron of jet fighters and a nuclear ballistic missile. There is one major Helicarrier, which is the one that is most important and used. There are also many smaller Helicarriers, however, which all serve as bases too. The Helicarrier has an extremely high level of security-even if someone managed to get on without clearance, guards and extremely powerful security technology would have them gone in a second. The Helicarrier was first proposed by Stark Industries, and was designed by Tony Stark.