I had been working on an architectural project with my 4x5 for some time and not really getting the results that were in my head and I was getting frustrated. Somewhere along the line I had accidently bought and cross processed some Ektachrome while simultaneously figuring out exactly how to get the result above on one negative..... this was that first 'success' of merging all those accidents together.
What most don't know is it took me 6 months and a lot of used 4x5 sheets to get the exact image in my noggin. I tried at night, in the day, from one side of the building to another etc etc. I knew 'exactly' what I wanted but couldn't get it, then on one late winter afternoon with the dipping sun bouncing around the city skyscrapers I schlepped all the gear over for one last bash, walked a different way, with another different vantage point and bam! My take on The Gherkin was done.
I did one other image like this "The Guggenheim" and then the project sort of went another way, but at least I know how I did it in case there's a next time!