Hi Demeter. Think what you would find above, below, to the left and the right of this map. There are four such items and replace one letter in each using one out of D, C, L, X for each to make a proper noun but leaving non-words behind.
I've finished except for the shading. I agree with a comment elsewhere that it spoils the puzzle as it is unnecessary and a little ambiguous, especially in the west, to my mind at least.