Where to keep Delphi DCU files?

Currently I have not set any specific output directory for Delphi DCUs in my main project. This results in the DCU files ending up in the same directory as my .pas source files. To me, this feels ugly as I don't like the idea of mixing .pas and .dcu files in the same directory. What is the best practice for storing Delphi .dcu files - keep them all one directory for each project? Or maybe create one DCU directory for each source folder? Any ideas welcome.

The best way to do it is to create a DCU folder for each project, especially if you have more than one project that uses the same files. Otherwise, you can end up with different compiles with different compiler settings stomping each other's DCUs.