Yellowstone Park

The start of the Danube River near St. Martin's Church. Somewhere, I have a picture of it taken with an old Kodak camera with 126 film in 1977.

The Grand Canyon

Lookout Mountain near Chattanooga. See 7 states at once.

Grand Canyon

Devil's Tower, Wyoming made the biggest impression on me.

Grand Canyon. Once seeing it in person. The second time seeing it was on a flight to San Diego as we were flying over it at sunset. If the flight had been on time, we would have not seen it at sunset on a crystal clear night. Instead we were about 2 1/2 hours late and what a surprise.

@billybob : I have flown over it too. It is an amazing sight! Flying over Bryce and Zion National Parks is great too. Unfortunately, I have not been to any of the three on the ground.

@RambleOn : Before or after seeing Close Encounters ? Haven't been there in person, but would be a spot to see. We took a helicopter ride over and in the Grand Canyon and would certainly vote for it.

@mypeez : Before! I have never seen Close Encounters. I was in high school when we made the trip that included Yellowstone and Devil's Tower. That's how strong the impression was.

The Sonoran Desert in bloom.

I've had a hard time coming up with an answer; maybe I'm trying too hard. So I have the Arches National Park under the stars, the Appalachian Mountains in North Carolina during a misty sunset, and this ...

Take me back, take me way, way, way back
On Hyndford Street
Where you could feel the silence at half past eleven
On long summer nights
As the wireless played Radio Luxembourg
And the voices whispered across Beechie River
In the quietness as we sank into restful slumber in the silence
And carried on dreaming, in God
And walks up Cherry Valley from North Road Bridge, railway line
On sunny summer afternoons
Picking apples from the side of the tracks
That spilled over from the gardens of the houses on Cyprus Avenue
Watching the moth catcher working the floodlights in the evenings
And meeting down by the pylons
Playing round Mrs. Kelly's lamp
Going out to Holywood on the bus
And walking from the end of the lines to the seaside
Stopping at Fusco's for ice cream
In the days before rock 'n' roll
Hyndford Street, Abetta Parade
Orangefield, St. Donard's Church
Sunday six-bells, and in between the silence there was conversation
And laughter, and music and singing, and shivers up the back of the neck
And tuning in to Luxembourg late at night
And jazz and blues records during the day
Also Debussy on the third program
Early mornings when contemplation was best
Going up the Castlereagh hills
And the cregagh glens in summer and coming back
To Hyndford Street, feeling wondrous and lit up inside
With a sense of everlasting life
And reading Mr. Jelly Roll and Big Bill Broonzy
And "Really The Blues" by "Mezz" Mezzrow
And "Dharma Bums" by Jack Kerouac
Over and over again
And voices echoing late at night over Beechie River
And it's always being now, and it's always being now
It's always now
Can you feel the silence?
On Hyndford Street where you could feel the silence
At half past eleven on long summer nights
As the wireless played Radio Luxembourg
And the voices whispered across Beechie River
And in the quietness we sank into restful slumber in silence
And carried on dreaming in God.

@RambleOn : My wife and I were in Rapid City SD last summer and drove over to devils tower "just cuz we're close".
It's easy to see why native Americans consider it sacred. It's special.

….

Unusual … probably Craters of the moon national monument.From the parks website
" Craters of the Moon is a vast ocean of lava flows with scattered islands of cinder cones and sagebrush. We invite you to explore this "weird and scenic landscape" where yesterday's volcanic events are likely to continue tomorrow."