[HttpPost]
    public IActionResult Itinerary(string[] destination)
    {
        foreach (var item in destination)
        {
            _context.Itinerary.Add(item);  // error: '"Argument 1: Cannot convert from 'string ' to NameSpace.Model.Itinerary"
        }

        _context.SaveChanges();
        return View();
    }

function createMarkers(places) {
    var bounds = new google.maps.LatLngBounds();
    var placesList = document.getElementById('places');
    for (var i = 0, place; place = places[i]; i++) {
        var image = {
            url: place.icon,
            size: new google.maps.Size(71, 71),
            origin: new google.maps.Point(0, 0),
            anchor: new google.maps.Point(17, 34),
            scaledSize: new google.maps.Size(25, 25)
        };
        var marker = new google.maps.Marker({
            map: map,
            icon: image,
            title: place.name,
            animation: google.maps.Animation.DROP,
            position: place.geometry.location
        });

        var checkbox = document.createElement('input');
        checkbox.type = "checkbox";
        checkbox.name = "destination";
        checkbox.value = place.name;
        checkbox.id = "id";
        checkbox.setAttribute("asp-for","LocationName");


        var label = document.createElement('label')
        label.htmlFor = "id";
        label.appendChild(document.createTextNode(place.name));


        placesList.appendChild(label);
        placesList.appendChild(checkbox);

<div multiple id="places" > </div>
    <button id="more">More results</button>

<input type="submit" value="Finished"/>