diff --git a/ontology/saref4wear.ttl b/ontology/saref4wear.ttl
index fa130f3392e7bb42a510de1007f5bd1b55e9f467..02d47b135753e90bd4eb29527a5f737c2220bc2e 100644
--- a/ontology/saref4wear.ttl
+++ b/ontology/saref4wear.ttl
@@ -11,6 +11,7 @@
 @prefix geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
 @prefix geosp: <http://www.opengis.net/ont/geosparql#> .
 @prefix saref: <https://w3id.org/saref#> .
+@prefix s4city: <https://saref.etsi.org/saref4city#> .
 @prefix s4wear: <https://saref.etsi.org/s4wear#> .
 @prefix dcterms: <http://purl.org/dc/terms/> .
 @base <https://saref.etsi.org/saref4wear#> .
@@ -233,9 +234,9 @@ saref:relatesToProperty rdf:type owl:ObjectProperty ;
 foaf:name rdf:type owl:DatatypeProperty .
 
 
-###  https://saref.etsi.org/s4wear#capacity
-s4wear:capacity rdf:type owl:DatatypeProperty ;
-                rdfs:domain s4wear:Area ;
+###  https://saref.etsi.org/s4wear#hasCapacity
+s4wear:hasCapacity rdf:type owl:DatatypeProperty ;
+                rdfs:domain s4city:Facility ;
                 rdfs:range xsd:long .
 
 
@@ -330,8 +331,26 @@ geo:Point rdf:type owl:Class ;
                 rdfs:label "Point"@en .
 
 
-###  https://saref.etsi.org/s4wear#Area
-s4wear:Area rdf:type owl:Class .
+## https://saref.etsi.org/saref4city#AdministrativeArea
+s4city:AdministrativeArea rdf:type owl:Class ;
+                          rdfs:subClassOf geosp:Feature ;
+                          rdfs:isDefinedBy <https://saref.etsi.org/saref4city#> ;
+                          rdfs:label "Administrative area"@en .
+
+
+## https://saref.etsi.org/saref4city#CityObject
+s4city:CityObject rdf:type owl:Class ;
+                  rdfs:subClassOf geosp:Feature ,
+                                  s4wear:PhysicalObject ;
+                  rdfs:isDefinedBy <https://saref.etsi.org/saref4city#> ;
+                  rdfs:label "City object"@en .
+
+
+## https://saref.etsi.org/saref4city#Facility
+s4city:Facility rdf:type owl:Class ;
+	            rdfs:subClassOf geosp:Feature ;
+                rdfs:isDefinedBy <https://saref.etsi.org/saref4city#> ;
+	            rdfs:label "Facility"@en .
 
 
 ###  https://saref.etsi.org/s4wear#Biometric