Hala Koszyki is a beautifully restored 1908 covered market in Śródmieście that reopened in 2016 as a high-quality food market and social space. The Victorian iron-and-glass structure houses around 40 food stalls, restaurants, and bars. The quality is genuinely high: good coffee, natural wines, Japanese food, local charcuterie, craft beer, fresh pasta, and Polish street food all under one roof.
It is more expensive than eating out generally in Warsaw but less so than comparable spaces in London or Paris. Go for lunch or an early evening drink — the hall is large enough that it doesn't feel crushingly crowded even when busy. The architectural restoration is excellent; the building feels like what it is.