Index: trunk/resources/data/defaultpresets.xml
===================================================================
--- trunk/resources/data/defaultpresets.xml	(revision 16930)
+++ trunk/resources/data/defaultpresets.xml	(revision 16938)
@@ -1633,4 +1633,5 @@
             <key key="barrier" value="city_wall" />
             <reference ref="optional_height" />
+            <check key="two_sided" text="Two-sided" disable_off="true" />
             <combo key="material" text="Material" values="adobe,brick,concrete,glass,masonry,metal,plastic,reinforced_concrete,steel,stone,wood" />
         </item> <!-- City Wall -->