Skip to the end.. Ish [Agents of SHIELD SPOILERS for UK]

Oh. My. GOD.

The Writing on the Wall was tense. I really thought Coulson might've flipped his lid for sure!

We got more squick-scenes like this;

And confirmation that more SHIELD agents had been to "the magical place" than just Coulson and Tattoo Man (from a previous episode, who uses his body as a canvas the same way Coulson uses a blank bit of wall).

Including an agent-turned-memory-wiped-artist, whose works definitely seemed familiar;

All of which..

The final scene shows what, yet another former agent inadvertently discovered, seems to be a 3D map of a city! 

Alien? Well yes, one line in the episode seems to hint that the big blue alien, whose blood had been used to revive/cure all of these agents, is "older than the pyramids"- or, at least, the mystery of him is.

I couldn't help but wonder what all this is leading too.. Especially in the lead up to Age of Ultron and the potential of the Civil War storylines that the movies are steam-rolling towards. 

Some Tumblr users have speculated that Skye's line "it's a map to knowhere", should be taken literally- that it's a map of Knowhere, as seen in Guardians of the Galaxy. But I can't see much point in that. Guardians and SHIELD may exist in the same universe, but neither SHIELD nor HYDRA have to capability to leave the planet to get to Knowhere. And even if they did, it would be a struggle to find it or get past the Guardians or the smugglers or Nova Corps or pretty much every space-going race out there! And no offence, but that map doesn't seem to conform to the outer dimensions of Knowhere (which is an alien slum/waystation/flea-market- not a place advanced civilisations would willingly live, surely?).

Personally it would make much more sense for the map to be of an alien city buried on Earth, Stargate Atlantis style. In fact a quick internet search shows the final puzzle looking not-to-dissimilar to plans of the Teotihuacan pyramids of Mexico; 

 Imagine this, but 3D. And more alien-looking..

It has the look of being built underground (or at least embedded in a bigger structure, maybe internal layout of a ship?).

Of course this is all speculation and conjecture. But considering all the powerful assets HYDRA are gaining, or trying to gain, it wouldn't surprise me if a city-ship wasn't in the MCUs future. After all, if further speculation is correct, and Skye's crazy-ass father is a Skrull, then how would he have gotten here? Maybe this city is what he came to Earth to find? 

It's all very intriguing either way..