Agents Of SHIELD: 8 Ways It Sets Up Marvel's Inhumans
2. Attilan
The strange markings that Coulson was making when possessed by the Kree blood within him turned out to be the blueprints of an ancient city, hidden underneath Suan Juan in Puerto Rico.
This was a city built by the Kree upon their arrival on Earth thousands of years ago, chosen to be the location where those humans deemed worthy would be transformed. It is here that the true power of the Diviner can be unleashed, and this is where it is opened and the Terrigen Mists released, turning Skye and Raina.
It was suspected that this city could well be Attilan, home of the Inhumans in the comics, although it is never specifically referred to as such. Given it was destroyed, it seems as though Attilan will be saved for the movie.
It has at various points been in the Northern Atlantic Ocean, the Himalayas, and inside a Kree city, so with the destruction of this location it could be the catalyst for having to move the city for the Inhumans film, and at the very least sets up the idea of these ancient cities.