Over at Industrial Light & Magic's terrific YouTube channel, they break down VFX for some of their biggest projects. Two of the most recent videos focus on Captain America: The Winter Soldier and Transformers: Age of Extinction:

And here's just one example of many where they go more in-depth about their process, this one is for Star Trek Into Darkness:

The amount of layers and objects on-screen at one time in these films is absolutely mind-blowing. We see so much CGI these days that it's easy for our eyes to just glaze over and accept it, but it takes huge teams of people to put together these shots and create worlds that have never existed before. In the previous Transformers film, one particular creature took 72 hours a frame to render. Yes, that's only one scene, and it took a full 3 days just to render one frame:

We take those kinds of things for granted when we sit down in a theater to watch the newest "turn off your brain" blockbuster, but the craft and the expertise that goes into making these films is absolutely world-class. 

For more incredible breakdowns, check out the ILM VFX page.