What is the best way to create a Website with multiple Functions with IIS, ASP.NET, MVC

I would like to build a website. Currently the way things are set up in my environment is that we create a Website in IIS, then off of that website we create multiple applications per department that we build a website/app for. Eg:

• http://ift.tt/2b9ntvW
• http://ift.tt/2aXt9FT
• http://ift.tt/2b9niRh
• http://ift.tt/2aXsG6K

This works for the case that each application is totally separate from the others in terms of functions, look and feel. An alternative to this approach could also be to have completely different websites. But this just saves us a few resources.

But what if I want to build a website that does maintain the same look and feel with multiple applications stemming from it? I have looked into this a lot and there doesn't seem to be any great plug-n-play options.

This leads me to want to create a single MVC application as our website and allow it to house all of the various functions we need, for example:

• http://ift.tt/2b9ndNi
• http://ift.tt/2aXsLY9
• http://ift.tt/2b9mGeB
• http://ift.tt/2aXtbxq

As you can see this website/MVC project could get quite large and could have several functions that could technically be extracted as completely separate projects.

Will this become a problem? Is there a better approach? What is the best approach?