What have been the most beautiful and interesting places (countryside/building/city) in the US and worldwide that you have seen/visited?

Rafting adventure trips from https://advantagegrandcanyon.com/

So far, Disney World! I like their Epcot theme park where you get a taste of just about every culture (from food to fashion) & meet natives from that land!

 The Louvre in Paris sucks. Terribly overrated. The Rijks museum in Amsterdam is way better.

Worldwide, in general the scenery in Austria and Switzerland takes some beating. 

There are a lot of places where there spectacular natural beauty - they're different, but still spectacular. I don't really see any way to choose one among them. Maybe Keukenhof Garden in the Netherlands when the tulips are at their peak, of one of the National Parks like Yosemite or Yellowstone. Or there are Canyonlands, Zion, Arches, Capitol Reef ... Bavaria is a beautiful area or maybe Iceland especially around Gullfoss. Or the sunset over the Gulf of Mexico from my back deck when I lived in Panama City Beach.

Grand Canyon

Cumberland Gap

I live near Chicago and love to see it all lit up at night against the lake. Beautiful. 

Notre Dame Cathedral in Paris

Lourve in Paris

Grand Canyon

Blue Ridge Parkway in Virginia 

Biltmore Estate in Asheville, NC (that town is great too)

Pacific Coast Highway

Gettysburg National Park in PA

St Patrick's Cathedral in NYC

most beautiful scenery:

Norway fjords, Scotland, New Zealand, Rocky Mountains in Colorado, Mount Fuji, Guilin provnce in China

most interesting cities:

London, Paris, St. Petersburg and Moscow (Russia), Tokyo, Berlin

buildings: 

Sydney Opera, Burj al Arab, Taj Mahal, Forbidden Palace Beijing. St Basilica Moscow, Castle Neuschwanstein, Chambord Palace

Monte go Bay in Jamaica, Dubai, Milan, St Petersburg (Russia), Krakow and Niagara Falls are some of my favourites. The first five particularly because of how friendly and helpful the people where in each of those places.

Back about 35 years ago, my ex and I drove out to Colorado.  We visited Colorado Springs/Pikes Peak and also the Canon City/Royal Gorge areas.

It was awesome.