>I'd like to see some idea of what they mean by big. An order of magnitude in terms of lines of code and the number of engineers they had for the job and how long it all took versus how long the original took to write etc.

Yeah, at my last place before I left, they were looking to do a rewrite of their main project that had been the result of years of hundreds of developers working on it. The time-scale was wooly, but was expected to be between 5 and 10 years and probably require ~200 developers and testers.

This was rewriting millions of lines of code, very little would be reusable.

I don't know if they went ahead with it or not, but it was looking like it would descend into chaos.