Why was the construction of Narbonne Cathedral never completed?

Construction of the huge Gothic cathedral began in 1272. Only the choir (one of the highest in France at 41 metres) and part of the transept were ever built. Around 1340 the project was stopped because extending the nave would have required breaking through the city’s defensive walls. The city consuls refused, as it would have left Narbonne vulnerable to attack. The Black Death in 1348 and lack of money made it impossible to resume later.