The history of Absalom's Black Market is shrouded in secrecy, as of course it is a den of Illegal dealings. Although it was never 'founded' by the city architects or any standing member of the society, rumors will no doubt float about the crowds of it's existence. Nestled in a remote location within the Puddles the black market is the go-to place to find all the not so legal goods that one could want. Finding an entrance to the Black Market is difficult for anyone without ties to the Thieves guild, simply because if you do not need to find it, likely you won't find anything other than a shady shop with hardly anything of quality within their shelves. Those who gain or are worthy of knowing where the Black Market is located are usually watched over by the Thieves guild, while the organization does not condone the marketing of goods, it is keen as to who knows about the goods in question. The Thieves guild also acts as the market's own guard, watching deals of great importance from the shadows and dealing with any 'issues' that may arise, though if anything is stolen that is the risk of working in such a dark corner of the trade.
Aside from being the prime host of illegal goods moving within the city, the Black market has also had an astounding impact on the overall safety and income of the city. The Thieves Guild keeps tabs on the products moving in and out of the market and where they are being distributed if the importance or danger is great enough. This self-sufficient protection allows the market to remain notably undetected from the prying eyes of the City watch, while keeping volatile goods within the hands of those items away from the hands of those that would mean the city and the factions within it harm. The economical benefit of the Black Market has been seen through generous 'donations' on part of the Guild and the attendees of the market, buyer pays seller, seller pays a fraction to the guild, and the guild uses some of the coin to keep the trade in the city flowing.