An art installation is slated to begin being set up along a 1-mile stretch of Main Street this week. Sculptor Hannah Verlin’s new work, “Thoughts Are Free,” will be featured on 15 telephone poles and one brick wall along the route. The installation is tied to both the Medfield Cultural District and to the town library’s Medfield Reads program, which is exploring Aaron Lansky’s book, “Outwitting History.’’ Each site will have a line from a poem, “Thoughts Are Free,” written during the Nazi occupation of Europe. The words will be printed in English and Yiddish on pieces of white paper, which will be layered together and left to the elements. “The bright white letters will be mounted on telephone poles and will be visible as people walk or drive through town,” said Jean Mineo, the project’s manager. “It can also be seen as a kind of treasure hunt to find all of the sites and complete the poem.” The installation will be up until October. For more information, contact Mineo at JeanMineo@aol.com.