Server.MapPath("/") return my site root not iis root

Server.MapPath("/") return my site root not iis root
I use visual studio 2012 & iis 8 on windows 8. When i use Server.MapPath("/") it is return MySite root not the iis root
Ex:
return
C:\inetpub\wwwroot\MySite
Not
C:\inetpub\wwwroot\
...