Hi Jakob

You could always set a Canonical Url to avoid being penalised for multiple urls to the same content: https://support.google.com/webmasters/answer/139066?hl=en

Is the data for each house stored in Umbraco ? with a nicer Url ?

if so I would probably implement an IContentFinder to look for incoming requests in the format /Details/Town/House, I'd use the Id or the path to locate a corresponding house in Umbraco (by storing the Id/Path as a property in Umbraco), if one was found I'd 301 redirect to the house details with the nice url:

 public class FindContentByHouseId : IContentFinder
    {
        public bool TryFindContent(PublishedContentRequest contentRequest)
        {
            // return false as soon as we realise there is no match.
             var path = contentRequest.Uri.AbsolutePath;
            // lets see if this path is specified in the houseUrl field on any of our 'house pages' content items in the cache
            var umbracoHelper = new UmbracoHelper(UmbracoContext.Current);
            var matchingContent = umbracoHelper.TypedContentSingleAtXPath("//HousePage[houseUrl/text() = '" + path + "']");
            if (matchingContent == null)
            {
                return false;
            } 

            contentRequest.SetRedirectPermanent(matchingContent.Url);
                // tell the umbraco pipeline we've found the content, no need to process any other rules
                return true;
        }
    }

If the data for the house resides outside of Umbraco then you could map a custom MVC route for your Url through Umbraco to a Custom RenderMvcController

RouteTable.Routes.MapUmbracoRoute(
      "House details",
      "Details/Town/House/{id}",
      new
       {
            controller = "Housing",
            action = "Details",
            id = UrlParameter.Optional  
 }, 
new UmbracoVirtualNodeByIdRouteHandler(1234) );

You could then create a HousingController that inherits from RenderMvcController, with a Details Action to handle the request

 public class HousingController : RenderMvcController
    {
        public ActionResult Details(RenderModel model, int id)
        {
// use the Id to retrieve the house data from the external source
// create a Custom View Model that inherits RenderModel
// pass this to your view
            var houseInfo = HouseService.GetById(id);
            var vm = new HouseViewModel(model.Content, houseInfo);
            return View(vm);
         }
}

You may be wondering where the model.content comes from... this will contain the IPublishedContent from Umbraco for the node 1234, specified in the VirtualNodeRouteHandler in the Custom mapped route:

UmbracoVirtualNodeByIdRouteHandler(1234)

This gives your external data an 'umbraco context' so if your templates have macros/functionality that builds for example a breadcrumb or similar out of the Umbraco content tree, they will still work, even though your house info is not stored there...

You can implement your own logic for finding an appropriate Umbraco page for context purposes if you wish, by creating your own VirtualNodeRouteHandler

eg

 public class FindHousingContextRouteHandler : UmbracoVirtualNodeRouteHandler
    {
        protected override IPublishedContent FindContent(RequestContext requestContext, UmbracoContext umbracoContext)
        {
 var umbracoHelper = new UmbracoHelper(umbracoContext);
// find an IPublishedContent item of your choosing, or indeed construct your own Virtual IPublishedContent item...
}
}

More info here: http://shazwazza.com/post/custom-mvc-routes-within-the-umbraco-pipeline/

regards

Marc