CNN report on a new $578,000,000 school opening in L.A. Yes, that's five hundred seventy eight million dollars.
OK, the CNN talking head is a complete twit, but yeah, that's waaaaay over the top.
Building from scratch, with a more modest design, and cutting out all of the gee-gaws, I'd estimate that you could do the project for ~$250M. If it was a brown-field project and there was soil remediation, that could push it up. But still.