c#中字段类型的不一致可访问性

我试图为我的程序做一些简单的类，我被字段类型错误的不一致的可访问性难住了我的Tile[，]类'theGrid'对象。我已经看了一些其他的解决方案，并将我看到的所有内容都设置为public，但我仍然卡住了，不知道该怎么做。

你能告诉我怎么修理这个吗?

public class Level
{
    public Tile[,] theGrid;
    public Tile[,] TheGrid
    {
        get { return theGrid; }
        set { theGrid = value;}
    }
    public static Tile[,] BuildGrid(int sizeX, int sizeY)
    {
        Tile earth = new Tile("Earth", "Bare Earth. Easily traversable.", ' ', true);
        //this.createTerrain();
        for (int y = 0; y < sizeY; y++)
        {
            for (int x = 0; x < sizeX; x++)
            {
                theGrid[x, y] = earth;
            }
        }
        return theGrid;
    }

下面是tile类的缩写:

public class Tile
{
    //all properties were set to public
    public Tile()
    {
        mineable = false;
        symbol = ' ';
        traversable = true;
        resources = new List<Resource>();
        customRules = new List<Rule>();
        name = "default tile";
        description = "A blank tile";
        area = "";
    }
    public Tile(string tName, string tDescription, char tSymbol, bool tTraversable)
    {
        resources = new List<Resource>();
        customRules = new List<Rule>();
        area = "";
        symbol = tSymbol;
        this.traversable = tTraversable;
        this.name = tName;
        this.description = tDescription;
        mineable = false;
    }
    public void setArea(string area)
    {
        this.area = area;
    }
}

 public static Tile[,] BuildGrid(int sizeX, int sizeY)         
 {              
      Tile[,] theGrid = new Tile[sizeX, sizeY];
      .... the rest of the code is the same
 }