Mark Leithauser, senior curator and head of design and installation, and Eric Denker, lecturer, National Gallery of Art. On the occasion of the exhibition Venice: Canaletto and His Rivals, the Mariners' Museum in Newport News, Virginia, has loaned the National Gallery of Art one of the world's oldest gondolas, once owned by American artist Thomas Moran. Leithauser and Denker discuss the legacy of gondolas.