With four smokestacks, the Omahas looked remarkably like the old four-stacker destroyers which they were to lead.  
Their armament showed the slow change from casemate-mounted weapons to turret-mounted guns. They held a full twelve 152mm guns, of which four were mounted in two twin turrets, one each firing fore and aft, and eight in casemates.  
The casemates were placed in the superstructure, not in the hull, as they had been on most previous classes, and were distributed with four guns firing forward and four firing aft. All casemates were also able to fire to the sides.  
Due to the large topweight lasting on these ships, only multiplied by the high-mounted catapults, the Navy removed two of the aft firing casemate-mounted guns in 1939.

    The vessels were the fastest U.S. cruisers at the time of their commision.

    None of these units saw active fleet duty which could be compared to the kind of duty the other cruisers had. Marblehead and Raleigh saw battle, the former in the ABDA forces in 1942, the latter in the 1943 Battle of Kommandorski Islands, in the Aleutians. Raleigh and Detroit were in Pearl Harbor at the time of the attack, and Raleigh suffered a critical torpedo hit.
 
    Several ships of this class saw service in the North Pacific ToO, including Raleigh, Richmond and Concord.  
All ships were serving in the Atlantic at least once during the war, however.