A profound, important half-to-full day — the ghetto museum, the Small Fortress and the columbarium make the Holocaust devastatingly concrete, and a guide deepens it immeasurably. The honest catch: it is emotionally heavy and not 'enjoyable' in any normal sense, logistics (museum + fortress are apart) need planning, and it's wholly unsuitable for young kids. Go for understanding, not sightseeing.
About 140,000 Jews passed through the Theresienstadt ghetto/transit camp; ~34,000 died there and ~88,000 were deported onward, most to Auschwitz-Birkenau. · encyclopedia.ushmm.org
The Ghetto Museum opened October 1991 after the Velvet Revolution; the Small Fortress was made a memorial to Nazi-persecution victims in 1947. · en.wikipedia.org