Luke Cage got his powers while incarcerated, which is neither the typical superhero origin story nor the typical jail experience. He was clearly being held in a special place to get that kind of treatment, so what is Seagate Prison on Luke Cage ? This location from Marvel comics is already a part of the MCU. There are some integral spoilers for Luke Cage ahead, so come back when you're done if you don't want to be spoiled.
On Luke Cage, Carl Lucas is betrayed by Willis Stryker and sent to Seagate Prison, which is located on an island off the coast of Georgia. He meets fellow Marvel characters there including Shades, Billy Bob Rackham, and Dr. Noah Burstein. It's also where he meets his wife, Reva Connors — who was later killed by Jessica Jones under Kilgrave's mind-control orders. There are rumors that prisoners are being experimented on, which turns out to be more than true.
However, Seagate Prison was first mentioned on screen in Iron Man 2. Justin Hammer, who was Tony Stark's rival billionaire playboy inventor, got sent there at the end of the film. It's also where Trevor Slattery, who posed as "the Mandarin" for Aldrich Killian in Iron Man 3 was imprisoned. In the Marvel One-Shot "All Hail The King," a documentary filmmaker checks up on Slattery, and then kidnaps him for an organization called the Ten Rings and the "real" Mandarin.
The entire One-Shot, which is available on the DVD for Thor: The Dark World, shows Justin Hammer there as well. You may be ready to put Iron Man 2 behind you, but Luke Cage has not. Hammer Tech plays a pretty significant role in the Netflix series. I half-expected to see Sam Rockwell in the finale, but Hammer appears in name only. Clearly, a lot is going on at Seagate that we don't know about in the Marvel Universe. I wouldn't be surprised if it shows up again.
Image: Myles Aronowitz/Netflix