Thankfully, nowhere! The option for an older template, such as minima, rounders, etc., has been moved from the top of the edit html section to the very bottom. Whew!
Unless you have a classic template from before 2006, you will want to click on 'Select Layout Template' (circled in purple above) to get to the templates that you were able to choose from before.
If you have accidentally chosen a new template and wish to go back to your old one, you can do so by going to your page elements page and clicking on 'edit html'. Scroll to the bottom as mentioned above. Your customization will be lost and you will have to start over again. This is why it is important to have a copy of your current template downloaded and saved to your computer. Downloading your template backs up the changes you have made to your template, while backing up your blog backs up your posts. You need to do both!
The fact that Blogger still allows people to choose from the classic templates (which were the choices before 2006) is a very good thing. That means that we will probably have access to the minima template for a long time.
The newer templates are a lot easier to use (I've heard) and offer simple ways to get advanced options, such as a three column layout. I will be exploring the new templates in the weeks to come!
Please do not copy and paste my words and images into your own posts. I work hard on my tips and wish for everything to remain on this blog. Want to share this tip with your readers? Feel free to link to this post: http://sneakymommablogdesign.blogspot.com/2010/06/where-did-old-templates-go.html Thanks! :)