These hills are alive with the sound of advertising. Hill, Holliday, Connors, Cosmopulos -- which does business as Hill Holliday -- is a full-service advertising agency operating through offices in Boston, New York City, and Greenville, South Carolina. It offers creative development and campaign management services along with media planning, brand promotion, direct marketing, customer relationship management, and corporate communications. In addition, the firm offers expertise in Hispanic marketing strategies. Clients have included Dunkin' Donuts, CVS, Chili's Grill & Bar, and Liberty Mutual. Founded in 1968, the agency is part of advertising services giant Interpublic Group.