From Treblinka, rather than return to Warsaw in the evening, you can travel on to Bialystok, near Belarus, a city with a Jewish tradition so strong that in 1913, Jews numbered 61500, or 70% of the population.
Of the one hundred synagogues and houses of prayer -the three main ones being the Groyse Shul on Szkolna Street, the Chorszul (Choral Street) on Zydowska Street, and the Pulkowa Synagogue -there remains almost nothing left to see, except for the nineteenth century synagogue at 3 Piekna Street, today the House of Youth and Culture.