Barely making a difference to what exactly? Your question suggests that you don't quite understand how some of the game-mechanics work. Markets have two 'multiplier' effects: a Tax-multiplier, and a Lux-multiplier, which are separate from each other, and neither is diminished at higher difficulty levels. However, the Tax-multiplier effect is vastly diminished in corrupt '1-shield towns', so I'll talk about that first (defining terms for clarity; apologies if you know any of this already): (As I understand it) a city's net commerce per turn (CPT) is the raw total of all the 'gold-piles' shown on the city-screen (obtained from roading and then working the surrounding tiles), minus any lost to corruption. This net CPT is then run through your Empire-wide slider settings (Tax% = 100% - Sci% - Lux%), and rounded down to the nearest integer values to give 'base' output values of Tax (gold per turn, GPT), Science (beakers per turn, BPT) and 'Happy faces' for that city, at a direct 1:1 ratio, e.g. in a city producing 10 uncorrupted CPT, at a T:S:L ratio of 4:4:2, you will get base values of 4 GPT, 4 BPT, and 2 Happies. The GPT (and also BPT) value is then increased according to any 'multiplier-building' augmentations applicable in that city (Markets+Banks+StockExes for GPT, Libs+Unis+ResLabs for BPT). Spoiler : Finally, the additional outputs from any Specialists are added to the augmeted values (1 Happy per Clown, 2 GPT per Taxman, 3 BPT per Scientist, 2 SPT per Civil Engineer; Policemen effects are slightly different). But that's not really relevant here, either. A Market increases a city's Tax (GPT) output by 50%, so its Tax-multiplier effect only becomes noticeable to your Treasury if your city is getting at least 4 GPT Tax income from the CPT-conversion. This is because the Market will turn the 4 CPT into 6 GPT, from which the Market's maintenance cost (-1 GPT) is than deducted, leaving you a whole +1 GPT better off than you were before you built the Market (although this still doesn't take into account the shields/ gold/ whipped citizens it took you to build the Market in the first place!). Spoiler : So in a city making 10 CPT, you would need at least 40% Tax (Sci% + Lux% ≤ 60%) to see any effect from a Market. A Tax-rate of 20-30% would only allow you to break even (2CPT @ 20%Tax * 1.5 = 3 GPT, -1 GPT Market-maintenance = 0 GPT net after the Market is built vs before), and Tax% = 0-10% would result in a net drain on your Treasury, because the Market-maintenance would cost more GPT than the Market was actually producing. To put it another way, if your Sci+Lux spending = 100%, with all CPT converted to Beakers + Happies, building Markets (and later Banks + StockExes) will do your income no (direct) good in any city -- rather the opposite! And by the same token, even if 100% of your city's CPT is going to Tax (i.e. Sci+Lux = 0%) building a Market in a 90% corrupt 1-shield town would be nearly pointless, at least from the point of view of increasing GPT. Since such towns are usually left small -- building an Aqueduct (-1GPT maintenance) to get the city beyond Pop6 would also represent a net drain on Treasury -- even with all 6 citizens out working the tiles, corrupt towns will rarely if ever produce more than ~20 raw CPT. At90% corruption, 20 CPT becomes 2 CPT net; at 100%Tax 2 CPT => 2 GPT, which a Market would convert to 3 GPT, so a Market in such a town would only just pay for itself. However, you might consider building Markets in captured 1-shield towns which will reach Pop7+ because they've been built on freshwater, or which have Aqueducts already (which you can't sell), because... The Luxury-multiplier effect increases the number of Happy faces produced by your available Luxes: Before you build a Market, you only get 1 happy face per hooked/imported Lux-resource type. So even with all 8 standard Luxes available (Incense, Dyes, Silks, Spices, Gems, Ivory, Furs, Wines), you'll never get more than 8 citizens happy per city. With a Market, the first 2 Luxes each make 1 person happy, the 3rd and 4th Lux each make 2 people happy, the 5th and 6th each make 3 people happy, and the 7th and 8th each make 4 people happy. So if you have all 8 Luxes, a city with a Market could have up to 2 + 4 + 6 + 8 = 20 happy citizens, barring War-weariness, etc... Spoiler : The Lux-multiplier effect has now become the main reason I build Markets in my core towns, since Markets are hugely more cost-effective than Temples, Cathedrals and Colosseums at producing Happiness. (I like building the Spaceship, which is a high-tech, long-game VC -- so I am usually running my Sci% at a high level to get through the tech-tree ASAP, and earning cash by selling obsolete techs, rather than increasing GPT from Markets+Banks). This effect is also why it gets more and more expensive to buy Luxes from the AI as your cities get bigger/more developed -- the AIs look at the total number of your people that each additional Lux will make happy across your entire empire, taking all Market-builds into account, and then raise their prices accordingly. Although it seems like an exploit to me, some CFCers have actually recommended to sell off Markets in high-shield core-cities/metropolii (where the extra Luxes will have the greatest effects) before making late-game Lux-import deals, so as to artifically lower the AI's asking price. Once the deal is done, they then immediately rebuild those Markets, and reap the Lux-Happiness rewards for the next 20T. (A town producing 50 SPT could rebuild its Market in 2T, or -- if the Treasury is healthy enough -- even 1T by disbanding a cheap mil-unit to put some shields in the box, then cash-rushing the rest). As stated above, the Luxury-multiplier effect only applies if you have 5 different Luxuries! Holding the global monopoly on e.g. Ivory won't make your citizens extra-happy, because only the first Lux of each type produces happiness (although the remainder are available for trading to the AIs, perhaps in return for their excess Luxes). TL: DR Don't build Markets in small corrupt 1-shield towns, or in any towns under Pop6 unless Tax% is >30-40% and/or you already have ≥3 Luxes available and Happiness is a problem. Markets are a much more efficient use of shields than Temples for making people happy, especially if you have ≥3 Luxes.