function show_location(str_location) {
    hide_locations();
    
    // set location pic & address visible
    var div1 = document.getElementById("pic_address_" + str_location);
    div1.style.display = "block";
    
    // set location title selected
    var img1 = document.getElementById("img_" + str_location)
    img1.src = "/images/location_title_" + str_location + "_sel.jpg";
}
function hide_locations() {

    // hide location pic & address
    var div1 = document.getElementById("pic_address_battersea");
    div1.style.display = "none";
    div1 = document.getElementById("pic_address_wimbledon");
    div1.style.display = "none";
    
    // set location titles to unselected
    var img1 = document.getElementById("img_battersea")
    img1.src = "/images/location_title_battersea.jpg";
    img1 = document.getElementById("img_wimbledon")
    img1.src = "/images/location_title_wimbledon.jpg";
}