Vandals have been at work in downtown Lawrence and nearby neighborhoods over the past few days.Graffiti, some of it described as unreadable and some as “readable and objectionable” by a Lawrence police spokeswoman, have been found at the following locations this week:An air conditioning unit and utility box outside Vermont Towers, 1101 Vt.; a traffic control box in the 200 block of West 11th Street; street signs at 18th and Illinois streets; on sidewalks and streets in the 1600 block of Louisiana; American Tower Corp., 925 Iowa; Sunflower Broadband building, 1 Riverfront Plaza; and the roof of the Lawrence Virtual School building and a bus, 2145 La.Lawrence Police are investigating.