<apex:page standardController="Venue__c">
    <apex:map width="400px" height="400px" mapType="roadmap"
              center="{!Venue__c.City__c},{!Venue__c.State__c}">
          <apex:mapMarker title="{! Venue__c.Name }"
                          position="{!Venue__c.Street__c},{!Venue__c.City__c},{!Venue__c.State__c}"/>
    </apex:map>
</apex:page>