Wow,
First of all, my uncle works for NASA and told me all about this one day.
While it may look like that shuttle is lifting off from the 747, it isnt, its faced up like that for Aerodynamics.
These 747's are used to transport the Shuttles from Manufactering location, to launch location. Although most of the time they are launced right from Cape Caniveral, were they are built.
[YOUTUBE]https://www.youtube.com/watch?v=qF7-fuB2OA4[/YOUTUBE]
[YOUTUBE]https://www.youtube.com/watch?v=kBy_Ec2Akhs[/YOUTUBE]
Also,
https://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft