If it was just water why is it brown?

I wonder if someone who restores artwork would be able to help you out.

The pattern where the paper got wet looks kind of cool. Maybe try getting the whole wall wet and see how it looks?

I was just wondering if someone smokes in the home. If so I thought this might be nicotine. If that's the case, it might be cleanable.

I still think it's likely soil that has accumulated on the wallcovering over the last 50 years. You don't have anything to lose,....... try washing it off.

You could paint the back wall red to create a feature wall and keep the others a lighter color like white or tan.

You could lighten up the room by adding a different light fixture or replacing the drapes, because they seem to be blocking out a lot of natural light.

I've had great success painting a dark room a dark color. It really makes the room feel warm and cozy. But you have to really pay attention to the lighting, and make sure you have the right amount of overhead, table and ambient lighting, or its really just a cave.

And all you really need to do is place some up lights in the corners, (they won't be noticed but will banish any dark spots) and remove the curtain tiebacks, pulling them to the inner edge of the window. You have a lovely home, and I hope you can fix the problem to your satisfaction.

Go for it, it will look gorgeous! And please post pics when you're done. I would still consider the up lights (you can get them at any big box store) for those areas that may look a little too dark, seriously, this can make a great deal of difference in how the room feels.

Accent walls are not typically found a historical homes.

Do you have this wallpaper in any closets? You might be able to remove a strip from an inconspicuous place and move it to the damaged area.

Perhaps you could just extend the drapery rod enough so that the drapes cover the damage.

That might mean the next time the thing leaks it will ruin the drapes, too.

Frankly, the wallpaper is not all that special (not as if it is a William Morris). I would just remove the paper from that wall and paint it with a color that is a match to the background of the paper.

Please consider though, that you do not live in a museum, and you are given some leeway in how you decorate. I personally wouldn't put Italian Moderne in your home, but an accent wall that ties into the wall paper would not be that big an anomaly from the period of the home. And if the unit develops another leak, it's wooden, fabric or leather panelling that gets ruined.

I like the idea of simply expanding the drapery rod and drapes

Expanding the drapery makes for a difficult time using the AC unit. Also since there is a fireplace and another window to the left of that image it opens a decor can of worms.

Having an old beauty myself I know that you get a weird cainotophobia with a tad of ocd'ism involved with changing anything original particularly if it's still in good condition. As with anything, you have to think what's appropriate for the home.

Sandi's home already has the wainscot Tudor type battens in the dining room and over the fireplace so fleshing out the corner isn't a stretch.

But if you paint it the background color of the wallpaper, won't that serve to "camoflage" the AC unit?

Perhaps a poultice with a peroxide or oxy cleaner would lift the demarcation. I would try a 3 minute on with a barely damp rag.

I have had a similar experience in the past, unfortunately you will not be able to remove the mark completely as applying more water can further damage it. I would suggest you paint the wall on this side of your room in a shade very near to the wallpaper and keep the end wall as a feature paper.

Wall paper companies like Thaibault, Brungswig and Fe, etc often still have historical patterns that they keep in stock. You might luck out if you know the name of the wall paper company and can send them a picture of the hung paper. Can you contact the wall paper company and see if they have another roll? I know there might be a color complication but if you truely want the same paper you might just find it. But I love the suggestion of an accent wall and you could do it the light background color of the paper?

sandiocd, the real question is this. Since you have established the fact that the paper has no historical value...

do you really like it? Or is it just easier to keep it? I bet that room would still look great if you just stripped the paper off and painted.

IF it's only that one stripe, the quickest and least expensive and most simple idea might well be to get an oak shelving board about six or eight inches wide, finish it to match either the window trim or the other wood in the room and then hang it on the wall vertically over the top of the stripe of stain, beginning from the baseboard all the way up to the ceiling or wood board trim at the ceiling ( cutting out around the white unit on the wall as needed), then hang something on it -- photographs, sconce, hanging basket w/plant, art, etc. - and, if you need a second one for on the left side of the window for symmetry, add a duplicate.,

Good work!

Crisis adverted!

Excellent solution! :)