Here's the less-touristy places I can recommend: Galway (Ireland) Bratislava (Slovak Republic) Chester, and Brighton (England - north and south) Aix-en Provence (France) Heidelberg (Germany) Piran (Slovenia)

I don't think in a city, I think in a country, and is Russia the country's best kept secrets, everything there is a mystery

Chernobyl - Ukraine Pripyat - Ukraine They were polluted during the Chernobyl Atomic Plant Accident in 1986. But they are still usefull for extremal tourism ;)