Can I open old Visual Studio Solutions (2005,2008, 2010,2013) in Visual Studio 2015 without upgrading the projects?

I read on Scott Hanselman's Blog, "I'm using Visual Studio 2015 to edit even .NET 2.0 apps so I'm not using older versions of VS," .

I also support old .Net solutions that open in previous versions of Visual Studio (2005, 2008, 2010, 2013). Is it possible with VS2015 to open these old solutions with out upgrading them?

I don't mind if they don't target the latest framework, it would just be handy to use a single version of Visual Studio rather than have 5 versions installed side by side.