Why do you think places like Venice and Barcelona became important trade centers?

ANSWER

Venice grew thanks:

1 - Its unique geographical location, which put it away from attempts to seize and/or siege it from the land side and made it extremely hard, if not impossible its investment by an enemy coming from the sea.

2 - Its fleet, which not only granted its defence and dominated the whole Adriatic Sea but also established a thriving stream of trades and a chain of settlements and naval strongholds all over The Central and Eastern Mediterranean and a chain of settlement.

3 - The monopoly in the trade of vital goods such as, for instance, the salt and the spices the Republic of Venice was able to impose to all the States and City-states

gravitating towards the Adriatic Sea.

4 - Its oligarchic, but well balanced government, which prevent the Republic of Venice from any attempt of establishing a Lordship and its policy which was aimed

to defend only its possession and commerciale routes, abstaining from territorial gaines dictated by the wish to dominate and conquest, as the other states of that time were accustomed to do.