diff --git a/doc/architectural/compilation-and-development.md b/doc/architectural/compilation-and-development.md
index fc849ff1b09..9f7a7dba5aa 100644
--- a/doc/architectural/compilation-and-development.md
+++ b/doc/architectural/compilation-and-development.md
@@ -17,7 +17,29 @@ To be documented.
 
 To be documented.
 
-## Documentation
+## Running tests ##
+
+### Regression tests ###
+
+The regression tests are contained in the `regression/` folder.
+They are grouped into directories for each of the tools/modules.
+Each of these contains multiple directories, each of which contains
+input files and one or more`.desc` files that describe what command
+to run, what output is expected and so on. There is a Perl script,
+`test.pl` that is used to invoke the tests as:
+
+    ../test.pl -c PATH_TO_CBMC
+
+The `–help` option gives instructions for use and the
+format of the description files.
+
+To be documented further.
+
+### Unit tests ###
+
+To be documented.
+
+## Documentation ##
 
 Apart from the (user-orientated) CBMC user manual and this document, most
 of the rest of the documentation is inline in the code as `doxygen` and
diff --git a/doc/architectural/folder-walkthrough.md b/doc/architectural/folder-walkthrough.md
index 9835af8a1c7..59e0b2aa43e 100644
--- a/doc/architectural/folder-walkthrough.md
+++ b/doc/architectural/folder-walkthrough.md
@@ -75,14 +75,12 @@ into the `doc/html` directory when running `doxygen` from `src`.
 
 ## `regression/` ##
 
-The `regression/` directory contains the test suites.
-They are grouped into directories for each of the tools/modules.
-Each of these contains a directory per test case, containing a C or C++
-file that triggers the bug and a `.desc` file that describes
-the tests, expected output and so on. There is a Perl script,
-`test.pl` that is used to invoke the tests as:
+The `regression/` directory contains the regression test suites. See
+\ref compilation-and-development for information on how to run and
+develop regression tests.
 
-    ../test.pl -c PATH_TO_CBMC
+## `unit/` ##
 
-The `–help` option gives instructions for use and the
-format of the description files.
+The `unit/` directory contains the unit test suites. See
+\ref compilation-and-development for information on how to run and
+develop unit tests.