if (document.getElementById("divLandscape_Feature") != null) {
    var rnum = Math.random() * 1;
    picknum = Math.round(rnum);
    if (picknum == 1) {
        $("#divLandscape_Feature").css('background', 'url(images/landscapephoto/london_photo2.jpg) center top');
    }
    else {
        $("#divLandscape_Feature").css('background', 'url(images/landscapephoto/london_photo1.jpg) center top');
    }
}