When a company files a notice of commencement for a project, it guarantees them lien holders right's, it's exactly what it sounds like. If a contractor was afraid they're not going to be paid they file a lien. When a company goes broke the court's pay off the lein's in the order that they were filed.
These days on large projects like this the final payment isn't released until a year after the project receives a Certificate of Occupancy for warranty reasons