There are a couple of spots in our neighborhood that I pass by on a regular basis, and at every passing I've thought that I should get a picture of it, but haven't. Either I didn't have my camera with me at the moment, or thought that I'd wait until the sun came out, or I was in a hurry, or whatever other excuse struck me at the moment.
One of these spots was this set of stairs. They belonged to a nearby empty apartment building that had been abandoned for so long the steps were completely covered by a thick layer of ivy. I loved it. It was like nature was reclaiming a few square feet of her territory. But the building was slated for demolition, and was wrapped up like a package with white tarp (pulled apart here for me to snap the photo), and the ivy was stripped away. Now the building is completely gone, and after letting countless opportunities go by to get the image I wanted, I've (hopefully) learned my lesson, and will remember to snap a picture the first time I see something that strikes me.