Customizing SharePoint 2010 global navigation
Use and activate drop down menu 1. First of all you need to use the browser and go to the root site from where you want to display the drop down. Click site settings and navigation and check sub sites. Updated: This will only work for SPS; you have to replace the Sitemap if it’s about foundation. See my comment down below. 2. Secondly you have to modify the menu control in the master page with help of SharePoint Designer. Change the property for MaximumDynamicDisplayLevels from 1 to 2 to get a drop down of two levels. Similar the above way we are using the left side navigation.