Index: trunk/src/org/openstreetmap/josm/data/validation/tests/SimilarNamedWays.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/tests/SimilarNamedWays.java	(revision 13978)
+++ trunk/src/org/openstreetmap/josm/data/validation/tests/SimilarNamedWays.java	(revision 13980)
@@ -53,4 +53,5 @@
         // See https://josm.openstreetmap.de/ticket/3733#comment:19
         addRegExprRule("\\pN+", "0"); // Unicode numbers: matches "Highway 66" but also persian numbers
+        addRegExprRule("M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$", "0"); // Roman numbers: matches "Building II"
         addRegExprRule("\\d+(st|nd|rd|th)", "0st"); // 3rd Ave
         addRegExprRule("^[A-Z] ", "X"); // E Street