Basic Information
The ancestor of the shopping mall the marketplace was the business hub of most urban areas until very recently.
At its simplest a marketplace is just a hole in the cityscape - an open area where traders can assemble to sell their wares - and in many places, particularly those too small, poor or primitive to have a permanent merchant population, it will remain just that.
Most places upgrade it pretty quickly though - it normally gets paved, to stop it turning into a dust bowl or a mud pool (depending on the season) and drained for much the same reasons. Many places will also construct (semi)permanent structures to shelter traders and/or shoppers and in hot countries (or ones with a lot of rain) the marketplace may be entirely roofed over for the comfort of all concerned.
Eventually a city may become big enough to get an assortment of market places for different things - dry goods generally like to be somewhere away from the livestock market for example. In a port city there may be one market near the docks specialising in imported goods and another on the landward side of the city for produce from the hinterland. Where slaves are traded, the slave market may or may not be a seperate venue.
Other amenities often follow - a water source is common, whether a well or a fountain - and some kind of sanitary arrangements are usually welcome as well. The buildings around the outside the marketplace will often end up playing host to inns, taverns and food shops attracted by the passing trade - this may be as well as or instead of stalls selling the same thing.
As well as trade and commerce a market place traditionally serves as a hiring place for casual labour and quite often a camp site for any travellers who can't find accomodation elsewhere (cited repeatedly in The Bible and doubtless elsewhere).
Tax officials, law enforcement (like a Court of Pie Powder) and money changers will also accumulate eventually and any gathering place will attract entertainers, rumour mongers and, in all likelihood, public trials and punishments as well. In any state where the opinions of the public matter, the marketplace will usually become a centre for public speaking and debate. This can get so serious that somewhere like Rome may even clear the commerce out of one of its marketplaces1 to some degree and devote the place wholely or partially to politics.
