public MonumentDetailPage(MonumentDetailViewModel viewModel)
        {
            InitializeComponent();

            BindingContext = this.viewModel = viewModel;
            this.Monument  = viewModel.Monument;
        }
        public MonumentDetailPage()
        {
            InitializeComponent();

            Monument = new Monument();

            viewModel      = new MonumentDetailViewModel(Monument);
            BindingContext = viewModel;
        }