Install-Package Microsoft.AspNet.FriendlyUrls

void Application_Start(object sender, EventArgs e)
    {        
        // Codice eseguito all'avvio dell'applicazione
        RegistraPercorsi(RouteTable.Routes);
    }
void RegistraPercorsi(RouteCollection routes)
    {       
        routes.MapPageRoute("home", "{lingua}/", "~/default.aspx");
        routes.MapPageRoute("chi-siamo", "{lingua}/{pagina}/", "~/chi-siamo.aspx", false, null, new RouteValueDictionary { { "lingua", "^(it|en)$" } });        
          
    }   

protected override void InitializeCulture()
    {     
        var contesto = HttpContext.Current;
        var routeData = RouteTable.Routes.GetRouteData(new HttpContextWrapper(contesto));
        if (routeData == null) return;

        contesto.Items["lingua"] = routeData.Values["lingua"];

        var lingua = Context.Items["lingua"] as string;
        switch (lingua)
        {
            case "it":
            case "en":            
                CultureInfo c = new CultureInfo(lingua);
                Thread.CurrentThread.CurrentCulture = c;
                Thread.CurrentThread.CurrentUICulture = c;
                break;
            default:
                
                Response.Redirect("/");
                break;
        }
        base.InitializeCulture();
    }

protected void Page_Load(object sender, EventArgs e)
    {     
        string lingua = CultureInfo.CurrentCulture.TwoLetterISOLanguageName;

        hlMenuHome.NavigateUrl = GetRouteUrl("", new RouteValueDictionary { { "lingua", lingua } });
        hlMenuChiSiamo.NavigateUrl = GetRouteUrl("chi-siamo", new RouteValueDictionary { { "lingua", lingua }, {"pagina", "chi-siamo"} });}