The top ship is USS Constitution. One of the original 10 United States-class 44 gun heavy frigates, ordered in 1794 and launched in 1797, she's the second oldest commissioned warship in the world after HMS Victory and the oldest warship afloat and seaworthy. She's made of American live oak and is legendarily durable; in combat with the HMS Guerriere the British cannonballs simply bounced off of Constitution's hull. One of her sailors, which one lost to history, shouted "Huzzah! Her sides are made of iron!" She carries the nickname "Old Ironsides" to this day. Most museum ships are transferred out of Navy ownership to a museum organization, but Old Ironsides is still in active commission under the Navy's History And Heritage Command, manned by a crew of 75 active duty officers and sailors. She can be visited at Pier 1 of the Historic Charlestown Navy Yard in Boston Harbor.
Bottom ship is USS Texas, BB-35, a New York-class battleship launched in 1912, she's the oldest surviving Dreadnaught era battleship. For her era, she's a marvel of forward thinking. She's the first battleship to mount anti-aircraft weapons, the first battleship to launch an aircraft, and the first battleship to use central directors and rangekeepers to aim the main battery, and the first American ship fitted with non-experimental radar. She was the first battleship in the world fitted with 14 inch guns, 10 of them in five double-turrets. She served in World War 1 and 2. In WWII she supported the landings in North Africa, Normandy, Iwo Jima and Okinawa, the only ship to take part in all four battles. Possibly her most famous moment was at Normandy, where the captain flooded one side of the ship in order to roll her over a little to gain more elevation and thus range for her main guns so that she could shell the Nazi defenses. Retired in 1948, the Texas was pretty much immediately preserved as a museum ship, the first of eight American battleship museums. She's currently undergoing repairs, upon completion of those repairs she'll be displayed in Galveston.