In 1300 what the largest city in europe with a population of 300,000 people

Fabian inherited some money from his family and decided to open a hardware store on his own. he bought the entire inventory on credit from vendors with the promise of paying them later. he hoped to have good sales when he opened the store because there weren't any other hardware stores in the area. however, he couldn't sell most of his stock because there did not seem to be any demand. he knew he wouldn't be able to pay the creditors from the money the store made. what kind of ownership does fabian have over his store? what kind of liability is fabian open to regarding the money owed to his creditors?