The renovation tapped a constellation of workshops, craftsmen, and companies around the country who combined ancestral techniques with modern engineering. Instead of entrusting it all to one company and its subcontractors, the task force split the project into more than 140 lots and opened up bids for each one.

Skills from across France

The renovation tapped a constellation of workshops, craftsmen, and companies around the country who combined ancestral techniques with modern engineering.

“If we are able to succeed and move forward, it’s because the skills are there,” said Mr. Jost, the head of the reconstruction task force. “You can’t rebuild a cathedral with good feelings alone.”

Instead of entrusting it all to one company and its subcontractors, the task force split the project into more than 140 lots and opened up bids for each one. Some of the 250 businesses involved were nationally recognized; others were tiny workshops with niche expertise. Often they joined forces.