I was an intern in the Microsoft Garage branch of the corporation. I worked with 3 other software engineers and a designer (all interns as well) in a team to create and design a product ground up over the span of 4 months.
There are two main offices in Boston, one on 1 Memorial Drive and the other is just across the street. Both offer amazing views of the city and are very close to a bunch of food/grocery places.
As a team designing and building the product from the ground up, you are given basically complete control over the product you build and how you want to make it happen. Of course there are restrictions and guidelines which are clearly provided by a small team of mentors. The pace is very quick and you should be prepared to learn alot in a very short amount of time - in order to do successfully.
The one downside is that you really have no idea how plausible a project is to realize in a 4 month period, thus defining a MVP (minimum viable product) early on and committing to finishing it can range from very easy, to nearly impossible by the end of the 4 months.
I worked an average of 8-9 hours a day 5 days a week.