In short
The great fire of 1871 destroyed Chicago, and its rebuilding produced the first steel-framed skyscraper in 1885. The city has been an open-air architecture textbook ever since.
Lake Michigan gives it forty kilometres of public shoreline, with beaches and an unbroken cycle path along the water.
What it really costs
Chicago is markedly cheaper than New York or San Francisco for a first-rank city. Central housing remains affordable by American standards.
The "L", the elevated train, covers the city well and runs all night on two lines. A car is not needed.
What nobody tells you
Winter is harsh: the wind off the lake pushes the feels-like temperature well below minus twenty, from December to February. That is not a cliché, it is measurable.
The Art Institute and the Field Museum are paid and expensive, but several institutions have free days reserved for Illinois residents. That does not apply to a visitor.
Safety varies sharply between neighbourhoods, more than the American average. The north and centre are walkable; some southern and western sectors are best avoided.