Enterprise Applications and Architecture

I'm not sure if you are specifically interested in examples or bare-bone frameworks for designing Enterprise applications, but you may want to check out the following discussion on Stack Overflow :

• Enterprise ASP.Net Architecture

The discussion features several examples and suggestions for laying out Enterprise applications that you could use to base your own upon.

You may also want to take a look at Microsoft's Patterns and Practices site, which covers best practices relating to designing all sorts of applications and has an area specifically for their Enterprise Library. Microsoft also has an Application Architecture Guide that might be worth looking into as well.

If you are looking for more code-centric examples, I would again suggest CodePlex or github to discover popular applications or more large-scale applications and downloading them and taking a look around

Regarding Accessing the Enterprise Library

The following links should help you get started : 

• Download the Enterprise Libary (It is also available through NuGet by searching for "Enterprise Library")
• Developer Resources for the Enterprise Library
• The Developer's User Guide to the Enterprise Library
• A Hands-On Lab and Tutorial for Getting Started with Enterprise Library