Is it possible to specify a sources folder in a Visual Studio project?

Generally project sources is placed where the project file is. In C++ projects you can specify include folders. In C#/VB you may edit .csproj/.vbproj file as text file and change what you want.

Also you can add existing items into project.

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You can simply add directories into your project. Open up the project in Visual Studio -> Right click on the project -> Add -> New Folder.

You can also link files into the project while they reside elsewhere.

Besides that, using those directories is quite uncommon in .NET so you should think about adapting the common habbits of the new platform to successfully develop for the new platform. Special-purpose solutions tend to do more harm.

In visual studio you can define a "default" root for all your projects. You do so by going to Tools -> Options -> Projects and Solutions and setting the first textbox "Projects location".

After that, you should know and follow how .Net projects are arranged.

Let's say you are creating a website called "TestSite". You will have a root folder with that name, and in that folder you will have a solution file "TestSite.sln" and as many subfolders as the number of projects your solution will be made of. A common scenario could be the following:

• TestSite.sln
  • TestSite.Bll
  • TestSite.Dal
  • TestSite.Web

That would be three projects, the first two of type "Class library" as they are your business layer and data layer, and the third of type "Web application" or "Mvc application" (which is much better).

You can reference the projects between them, and when you compile you get everything tied together.