Iframe or Similar in ASP.NET MVC Project!

Hi, first of all, sorry about my english!

I'm migrating an Intranet, from PHP to C# MVC. This intranet have a lot of systems inside it, and this systems got their structure(intranet layout and session).

We made a new project(ASP NET Web Application) called Intranet, and put some systems on it. But there is a large number of big projects that we'd not want to do into the intranet project, but we want to get the session and the structure from intranet. The main idea is, I sign in intranet(project MVC 1), and I access other c# projects(no need to sign in again). To do this, I only saw iframe, but it's old and don't look like to be good. There is another solution or something similar to iframe?

I will be grateful for any help.

Have a nice day!

Best regards,

Fabricio.