Developers' attitudes vary enormously - some see the discovery of archaeological remains as a nuisance and will even try to hide or destroy them (in the UK this is illegal, and surveys are carried out prior to and during works to check if there might be anything worth excavating).Others find it fascinating and will report anything of potential interest they find; some even employ archaeologists (my first paid job after graduating was with a construction firm, owned by a man who spent two weeks every year volunteering on archaeological digs) or sponsor archaeological teams.

@Jnei Of course a mixed bag. I heard that when filming a movie about Rome subterranean tunnels were opened and the workers could see that when fresh air hit the caverns that colors faded. Later, cameras were brought into the sites and the colors filmed. I think this was shown in Fellini's, "Roma."