If you see this tooltip when examining your break points “The break point will not currently be hit. No symbols have been loaded for this document” then you’ve found the same issue that has been driving me mad for a few hours, it must mean you’re new to debugging web sites as well!
Simple solution (sic) is to right-click on your solution file and select “Properties” and then under Common Properties->Startup Project select the “Multiple startup projects” and set whatever action you require against the project(s) you want to debug.
Simples! Applies to Visual Studio 2010 onwards, and not just VS2013 as I at first thought.