Dan Tassel is a photographer, collector, and retired physician from Massachusetts. With interests in historical photography and the Middle East, Tassel began a "then-and-now" project in Israel the 1980s. Inspired by 19th-century photographs of various historic and religious sites, Tassel traveled throughout the region, taking modern equivalents of images captured a century earlier by photographers Félix Bonfils, Francis Frith, C. and G. Zangaki, and others. This project resulted in an exhibition, curated by Tassel and displayed at the Harvard Semitic Museum, the Haifa Museum, and the Jerusalem Theater; and in a portfolio publication, Jerusalem Then and Now, published in 1985 in collaboration with the Harvard Semitic Museum. Tassel's photography collections, amassed over a period of 25 years, have also been exhibited at Harvard's Fogg Museum and its Fine Arts Library. In addition to the Dan Tassel photography collection at Brandeis University, there is a Tassel Collection of historical photos at Harvard's Fine Arts Library.