diff --git a/javadoc/xdocs/faq.fml b/javadoc/xdocs/faq.fml
index 57fbeb3a..db20722b 100644
--- a/javadoc/xdocs/faq.fml
+++ b/javadoc/xdocs/faq.fml
@@ -53,5 +53,49 @@ maven.javadoc.offlineLinks= \
         <source>maven.javadoc.additionalparam=-J-DproxyHost=${maven.proxy.host} -J-DproxyPort=${maven.proxy.port}</source>
       </answer>
     </faq>
+    <faq id="classdiagrams">
+      <question>How do I generate class diagrams on Javadoc pages using free tools ?</question>
+      <answer>
+        <p>
+          One solution is to use UMLGraph and dot (part of Graphviz).
+        </p>
+        <p>
+          When running the javadoc goal with the below configuration,
+          the UmlGraphDoc doclet generates class diagrams
+          into the package and class pages.
+          <ol>
+            <li>Put latest jar in repo/depend on UmlGraph jar, e.g.</li>
+<source><![CDATA[
+<dependency>
+  <groupId>gr.spinellis</groupId>
+  <artifactId>UmlGraph</artifactId>
+  <version>4.6</version>
+</dependency>
+]]></source>
+            
+            <li>Set Maven properties:</li>
+<source>
+maven.javadoc.doclet=gr.spinellis.umlgraph.doclet.UmlGraphDoc
+maven.javadoc.docletpath=${maven.repo.local}/gr.spinellis/jars/UmlGraph-4.6.jar
+maven.javadoc.usestandardparameters=true
+</source>
+            
+            <li>
+              Install dot (in <a href="http://www.graphviz.org">Graphviz</a>)
+              and put on PATH (so UmlGraphDoc can run it); e.g. for Windows:
+            </li>
+<source>
+GRAPHVIZ_HOME=(the path)
+PATH=%PATH%;%GRAPHVIZ_HOME%\bin
+</source>
+          </ol>
+        </p>
+        <p>
+          Refer to
+          <a href="http://www.spinellis.gr/sw/umlgraph/">UMLGraph</a>
+          docs for its custom Javadoc tags that enhance the generated diagrams.
+        </p>
+      </answer>
+    </faq>
   </part>
 </faqs>
\ No newline at end of file
diff --git a/javadoc/xdocs/properties.xml b/javadoc/xdocs/properties.xml
index 57fbe0cd..e7dbd1a1 100644
--- a/javadoc/xdocs/properties.xml
+++ b/javadoc/xdocs/properties.xml
@@ -63,6 +63,8 @@
             Specifies the doclet to use when calling javadoc. See
             <a href="http://ant.apache.org/manual/CoreTasks/javadoc.html">the 
             ant javadoc task</a> documentation for more detail.
+            See <a href="faq.html#classdiagrams">Class Diagrams FAQ</a>
+            as an example.
           </td>
         </tr>
         <tr>