They might be worth something.
This is an aerial view from the 1970s, showing the land around Orlando, Florida owned by Disney. An architect working at the firm that used the aerial as a design tool (as in the close-up below) snagged the large, mixed-media architectural drawing when the firm was going to ditch it. From free to $2,500 in 30 years, according to the Antiques Roadshow appraisal; not bad.
The appraiser noted a couple things worth passing along here. First, given the copyright of the drawing (by Disney, if I recall correctly), the current "owner" could sell it or have it insured for something like the above dollar amount, but he could not duplicate it and make many more dollars. Disney could do that...if they found a market willing to pay for such a thing.
Second, he pointed out the yellowing of the photo at the top of the page from sunlight, recommending that the owner keep it out of sunlight to reduce further damage. While I wouldn't argue with that recommendation, I'd say the yellowing makes it a bit more interesting. It almost looks intentional, like a Morphosis drawing before its time: