Poland's main destinations line up conveniently for a rail trip: Krakow in the south with an intact medieval core, Warsaw rebuilt from scratch after the war, Wroclaw with its Silesian squares and Gdansk on the Baltic. The contrast between what survived and what was reconstructed is the thread running through most of the country's cities.
The guides on this page cover Krakow, Warsaw, Wroclaw, Gdansk and Poland as a whole. Summer suits the Baltic coast and the lake districts; the cities themselves are comfortable from spring through autumn, with December adding Christmas markets. Trips to Krakow often include Auschwitz-Birkenau and the Wieliczka salt mine nearby — both require booking ahead and take most of a day, so they are worth slotting into the plan early rather than late.