Visualize the following scenario: A solution with three projects:

• {Project 1} ASP.NET Web Application - Containing 1 x .aspx file
• {Project 2} Class library - Containing my funky logic
• {Project 3} ASP.NET Web Application - [SET AS DEFAULT PROJECT] Containing Default.aspx [SET AS DEFAULT START PAGE]
  

(Project 3) Default.aspx calls my Class library (Project 2)to do its funky logic. Funky logic wants to instantiate the single .aspx file (Project 1) in the other web application.

Now to do this I would typically use BuildManager.CreateInstanceFromVirtualPath();. However I guess the context is Project 3 as thats where the request first started from.

How do I get hold of the aspx file in Project 1?

I don't think it is possible unless you expose a web service in project 1. Just to understand the context, why would you need to access a web page from business logic? If you can explain your requirements, we can identify alternatives. 

Well I created some code to generate HTML formatted e-mails. I use .aspx pages for the template for the HTML e-mail. However now I am coming to package it all up into an assembly I am running into the sticky situation of how to store the .aspx and the business logic.

I assumed that I would not be able to store the compiled .aspx in the same .dll as my class library (I may be wrong on that). Hence having a project for the .aspx file and a class library for the business logic.

So Project 3 is my main project I am worknig on. Project 2 is a reference to my business logic library (for sending emails) and Project 1 was the definition of the html for the emails.