What are the colors in the map? The rest of the room?

We have a large pottery vase on our mantle which we rotate out with seasonal fake foliage (a spring, summer, winter and fall set) and on the other side a lamp, but we need the light. Could also be a fantastic big candle stick or three. I know there are many lovely examples of these kinds of things in the boutiques in my small town. I was just at a craft fair last night and there were lots of candle displays. You might consider a lantern with a glass globe (called "hurricane lanterns"), which would also do double duty in case of a power outage.

Your room is neutral so, what's in your closet that could jump start a color way here? What outfit gets you the most compliments due to its color? Do you love it and would it work for this room? If so, you can take it with you shopping for pillows, art, candles.

I would add some greenery - maybe eucalyptus leaves in a glass vase. See below for some inspiration images. Good luck!

Houseplants are always a good way to add color and some organic shapes. You can also add some color with the plant's container.

Something like this might work? (From Pistil's)

Or an air plant in a metal container like this:

And I'm not sure how wide the mantle is, but vintage books might be a nice addition, with or without bookends.

(From Westelm:)

Kirkland's has quite a bit of decor that might work with your style. This lantern could be OK (link)

Distressed metal or wood candleholders like this would work:

You can also get colorful candles with neutral wood or metal candleholders or a lantern.

I think adding some color is a great idea. It looks like one of the butter crocks has some blue on it; picking up that color or adding some deep red would probably be good, or going towards a green depending on how it works with your walls. It sounds like you have a lot of neutrals going on, and the rustic antique style you have tends towards neutrals, so you'll have to be intentional about adding color if you want it.

I'd look for some good size OLD brass candlesticks -- you want the map to shine so you don't want too much on it and you have several things down below. Sometimes less is more.

There isn't really much in the way of color in the photo you provide, however what are the colors you have around the house? What is the color scheme you are using? If you said that the paint takes on a greenish hue, maybe try adding some green in accents colors around your home? You seem to have an (iron) cross on the wall and a lot of neutrals, so we wanted to share some of our designs to aid you in your dilemma. Note the color palettes in the rooms and the decor on the fireplaces.

If you have a Hobby Lobby by you, GO! I think the mantle could use greenery. Hobby Lobby has tons (tons!) of faux but real looking greenery.