Which historic military sites have been the most memorable for you?

I think the most memorable for me was Pearl Harbor

I live near Nancy KY where the Civil war battle of Mill Springs took place. There is a beautiful military cemetery, as well as a museum there. Just to walk among the veterans headstones on a quiet day, it makes you realize, and think of what an awful experience war is. You can almost feel their presence!
More Americans died in our Civil War than any other, today war is part of our life, a tragic part, my only hope is my grandchildren may see at least a short time out before the next one!

Point du Hoc

Andersonville NP. I'd read of places that seemed so quiet they were abandoned and at times, the stockade area is like that. At night (I do CivWar living history & have slept there as a POW), the place is ghostly.

Others that I was fortunate to visit. Ft Toulloise, Spanish Fort, Vicksburg, Gettysburg, Shiloh, Ft Sumter, Ft Moultrie, Antietam, Fredericksburg, Wilson's Creek, Ft Pulaski, Ft Clinch, Corinth, Harpers Ferry, Stones River, Chickamauga, Chattanoga, Resaca, Pickets Mill, Kennesaw, Bentonville, Tinian, Yorktown, Cowpens, Kings Mountain, Pearl Harbor, and Bunker Hill

Gettysburg and other American Civil War battlefield sites. When you consider the sheer number of deaths in a short period of time, it just enforces the fact that we who serve(d) in the Uniformed Services "Prepare for War, but Pray for Peace".
Overseas, seeing the Normandy coastline from the deck of a ship and having been a Navy Corpsman accompanying a Marine Honor Guard at Anzio was awe-inspiring as well.

USS Arizona (always a tear jerker when you see the names in marble); Corregidor with still intact coastal artillery guns and 12" mortars (at least in 1984); Wake Island where the Marines put up a heroic fight against Japanese and inflicted heavy casualties on them; Verdun and especially Fort Douaumont with its many undergound galleries and still intact guns in armored cupolas (nearly a millions casualties with an Ossuary contained the bones of fallen French soldiers); Bastogne and the grave of General Patton in the Luxembourg American Cemetery; Guadalcanal where I visited various battlefields (Henderson Field, the Tenaru, Edson's Ridge, Matanikaw) in our first offensive campaign against the Japanese (I dove on a sunken B-17 and two beached Japanese transports from the Japanese November offensive and near a local school I saw either a P-39 or P-400 Airacobra); Gallipoli which showed the futility of the British and ANZAC troops trying to take entrenched and well- defended Turkish positions that occupied the high ground (too many blunders); and finally Okinawa where I explored many battle sights such as Shuri Castle, Kakazu Ridge, Sugar Loaf, and others (I also participated in a joint American-Japanese war dead search (Japanese) on southern Okinawa. One of the AF ladies from Kadena found some Japanese finger bones while digging on a hillside. I was helping her excavate them and discovered that they were curled around a live Japanese Type 97 fragmentation grenade.)

The American cemetery outside of Manila, and Corregidor; the Arizona.

MEMORABLE.... there have been several.....from the Japanese memorial in Kyoto dedicated to ALL soldiers from ALL countries who died fighting in wars... to the changing of the guard at the tomb of the unknown soldier Arlington Virginia......but for me the most memorable was while I was serving as a tactical officer at OCS.....As an assignment I had the cadets plan a trip to the Army Navy game.....they had to do everything....from arraigning transportation..... to coordinating lodging.....even the purchase of tickets.....they did an outstanding job.....the entire class was on the 60 yard line surrounded by plebs from West Point ....... Everyone except I and my junior Tac officer..... We, dressed in full army uniform, had seats on the NAVY SIDE surrounded by Naval academy cadets...... NOW THAT WAS MEMORABLE

Also visited the Somme and Flanders battle sites in Belgium. Well documented and very well preserved museums and trenches.

The artillery museum at Ft. Sill, especially the Lance missile exhibits. Plus the Pershing equipment, Honest John and Sergeant rocket systems that came before Lance. Atomic Annie, the Redstone Missile, and of course all the cannon artillery scattered around the grounds and the artifacts inside.