Usage patterns
〈場所〉で市を開くto hold a market (at a place)
They hold a market in the square every Sunday.
〈物〉を市に出すto put something up for sale at the market
The farmer brought freshly picked vegetables to sell at the market.
市で〈物〉を買うto buy something at the market
I bought some fresh fish at the morning market.
Expressions
市に虎ありpeople will believe a falsehood if many repeat it; argumentum ad populum 市に虎を放つlet a fox into the henhouse; do something dangerous; let loose a tiger in the marketplace