System.Data.Spatial.DbGeography sample (Latitude and Longitude).

DbGeographyTryOut.cs

class Program {

    public class Db {

        public static Dictionary<string, DbGeography> Locations = new Dictionary<string, DbGeography>() { 

            //instert the place locations here...
        };
    }

    static void Main(string[] args) {
        
        // POINT(Long Lat)
        var myLocation = DbGeography.FromText("POINT(-117.861328 34.089061)");

        //Order by distance (nearest one is at the top)
        var locations = from location in Db.Locations
                        orderby location.Value.Distance(myLocation)
                        select location;

        //get the nearest 10 hotels
        foreach (var hotelLocation in locations.Take(10)) {

            Console.WriteLine(hotelLocation.Key);
        }
    }
}

Good example, Thanks