How to structure an enterprise MVC app, and where does Business Logic go?

In my apps, I usually create a “Core” project separate from the web project.

Core project contains:

1. Business objects, such as entities and such
2. Data access
3. Anything that is not specifically designed for web

Web project contains:

1. Controllers, which route requests from the UI to the core logic
2. Views, which focus on presenting data in HTML
3. View Models, which flatten/transform core business objects into simpler structures designed to support specific views

The key point here is that the web-based Models folder/namespace is ONLY used for presentation-specific models that document the specific variables needed for a given view. As much “business logic” as possible goes into the core project.