As fall sets in and the days grow shorter, the thoughts of many inevitably turn toward all things spooky. The folks at Cambridge Historical Tours (617-520-4030, cambridgehistoricaltours.org) are no different, as they offer an eerie and illuminating Ghost Tour throughout the Halloween season. Expert guides in Victorian-era costumes lead 90-minute walking excursions around Harvard Square recounting shocking tales of grisly murders and harrowing hauntings before ending, appropriately enough, at Cambridge’s Old Burying Ground. To keep it from getting too scary for young ones, “spirited” jokes are interspersed along the way. For those less inclined toward the morbid, don’t fret—the company also offers regular tours of both Harvard Square and the high-tech playground of Kendall Square.