The focus is the challenges presented by buildings under construction and the construction sites. Current features have revived and often amplified many firefighting challenges of a century ago such as pipe chases, common cocklofts, and floor lofts. Renovations have brought new construction challenges into older buildings, such as lightweight structural members, combustible materials, and stronger window glazing. Larger buildings, compressed construction time frames, and enhanced site access security have magnified the challenges of the past. Construction features, methods, materials used in buildings, and case studies of incidents will be presented.'