LIKE its wealthy Italian sisters across the mountains, the city of Nice in the 15th and 16th centuries was a place where great fortunes were piled up in the midst of misery. Moneylenders flourished, and when the long-suffering poor finally rose against their masters in 1437, they were brutally put down by execution and banishment. But the rich man's ways were in a sense a boon to posterity; there was no easier way for him to purge his sins or ease his conscience than by commissioning a rich altarpiece for some local chapel.
This summer, visitors to Nice have been learning just...