SPWeb.AlternateHeader property
SharePoint 2013
Gets or sets the URL for an alternate .aspx page that will be used to render the top navigation area in SharePoint Foundation pages.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
The AlternateHeader property applies to pages that are located in the \\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\1033 directory. This property specifies the URL of the page to execute instead of the standard top navigation area that is usually rendered in these pages.