The most important URL for a .NET developer

Get source implementation code for the entire .NET Framework!

 See how the experts code at Microsoft. 

Below URL is base code for Array implementation in .NET Framework.

Update moved to github in 2017 - 

referencesource/mscorlib/system/array.cs at main · microsoft/referencesource (github.com)

and looks like

I wrote this post because I keep on forgetting about this resource. You can download all documentation starting from Framework 4.5.1.