Ahead of Turkey starting accession talks with the European Union on 3 October, the BBC's Nick Thorpe sends the first in a series of snapshots from his journey down the EU's eastern border towards Istanbul.
In the large open-air market on the edge of Bialystok every price is quoted in both Polish and Russian, every sign is written in two scripts - Cyrillic and Latin.
In the slanting early autumn sunlight cheap goldfish and caviar, toys and jewels, but above all clothes are for sale here in dusty stalls beside a football stadium.
Only 50km (31 miles) from the border with Belarus, 100km from Lithuania, Bialystok is well placed for traders to take advantage of price differences in the three countries.
But that is now under threat. Poland and Lithuania joined the EU last year and visa controls make it harder for Belarusians to enter.
President Alexander Lukashenko of Belarus has also introduced tough restrictions on what can be taken into and out of his country.
Ludmilla still travels here every weekend from Grodno in Belarus to sell watches and scarves and takes Polish goods home to sell. But now she works in fear.
"Everything I'm doing here is illegal," she told me. "If Polish border guards visit the market and find me here they can stamp my passport with a deportation order and ban me from Poland for years. It's their new policy."
North of Bialystok, in Sejny, almost on the Lithuanian border, the Borderland Foundation was set up 15 years ago in a former synagogue to explore and rekindle the rich diversity of peoples and faiths in this area.
Catholic and Orthodox Christians are in the majority but there are still the remnants of Jewish and even tiny Muslim communities, descendants of Tatars who settled in the Middle Ages.
Kryzstof Czyzewski, of the Borderland Foundation, argues that the European Union must remain open to the east.
"There is no other way than to re-establish a bridge; not to establish a life on both banks of the river, of the societies separately in the kind of fortress or castle or tower, but to think how to rebuild a bridge - and that's my work."
And while the border with Belarus may be becoming harder to cross, he is encouraged by the easy flow across the Polish borders with Lithuania and Ukraine.