What is special about St. Paul’s Cathedral?

https://en.wikipedia.org/wiki/St_Paul%27s_Cathedral

https://www.bbc.com/search?q=St.+Paul%27s+Cathedral&edgeauth=eyJhbGciOiAiSFMyNTYiLCAidHlwIjogIkpXVCJ9.eyJrZXkiOiAiZmFzdGx5LXVyaS10b2tlbi0xIiwiZXhwIjogMTc2MjI5NzcyNywibmJmIjogMTc2MjI5NzM2NywicmVxdWVzdHVyaSI6ICIlMkZzZWFyY2glM0ZxJTNEU3QuJTJCUGF1bCUyNTI3cyUyQkNhdGhlZHJhbCJ9.KsAdZQZXpMzMpxgSZihEqUsu_lXoQJ1TrUq2nUNnhKs

https://www.bbc.com/reel/video/p0jnkzzy/the-giant-350-year-old-model-of-st-paul-s-cathedral

https://books.google.com/books?id=92ZZAAAAQAAJ&pg=133#v=onepage&q&f=false

St. Paul’s Cathedral is more than just an iconic architectural masterpiece designed by Sir Christopher Wren. It’s the seat of the Bishop of the Anglican Church in London, was the site of Winston Churchill’s funeral, and is where Lord Nelson of Trafalgar Square fame is buried. St. Paul’s also is a monument to the resilience of the British people who built it following the “Great Fire” of 1666 and later kept it from being destroyed by fire during the London Blitz of WWll.

Until 1963, St. Paul’s Cathedral was the tallest building in London. The cathedral’s dome is still one of the tallest in the world.

It's absolutely a special place. You've been given multiple links that explain why.
There's an iconic photo of the dome still in one piece during the blitz that became a bright symbol of resilience during the dark days of WWII. As it's said; beauty is only skin deep; there can be much more of real value beyond what's on the surface.

https://en.wikipedia.org/wiki/St_Paul%27s_Survives

PS: We found Milan's duomo to be pretty darn impressive even without doing the roof.

Ditto all the above. So much historical significance. A couple additional comments, Diana and Charles were married there. There is an American Chapel in the back of the church. It is in gratitude for U.S. assistance during WWII, and the sacrifice made by American troops. It was built as part of the repair following WWII. There is a book with a list of those Americans that lost their lives. Many famous people are interred in the crypt. You can take a free tour of the church, ask at the information desk. Outside the cathedral there is an exhibit depicting the cathedral during WWII.

I didn't visit St Paul's until my 6th trip to London, so it was not at the top of my must-see list, but now that I have, I wondered why I waited so long. I made it up the stairs as far as the Whispering Gallery, and enjoyed exploring all the nooks and crannies, especially the gravestones for various famous people buried there in the lower level. The history made it special, for me.

"What is special about St. Paul’s Cathedral?"

Because that is where Lord Rayleigh discovered "Whispering mode" waves of course. :)

https://en.wikipedia.org/wiki/Whispering-gallery_wave

[snip]
Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul's Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing, as well as in astronomy.

One of my happiest thoughts is all three of my kids ( separate trips ) and myself got to visit notre dame before the fire , at least 4-5 times .

It will never be the same renovated . I loved knowing I walked in the steps of millions of people over hundreds of years .

a must-see to one person is worth no more than a glance from another. Beauty is primarily subjective, though some mathematicians and scientists may disagree. Jean Kerr once remarked, 'Beauty is only skin deep. That's deep enough. What do you want, an adorable pancreas?' In that spirit, to me, St. Paul's is one of many and not special in any way. The same goes for Notre Dame in Paris. It's so white it hurts the eyes! No mystery. I'll take a gloomy Romanesque church over a Gothic one any day, though I find the Milan Duomo spectacular. I am also not impressed by which aristocrat or clergy built something, nor which famous person is buried there. The seven elements of art and how light makes it all come alive is what I travel to experience. I am sure everyone here has their reasons.

Extra nauga stars to RobertH up there in the northwest for bringing waves into the discussion, but keep in mind that the scientific community is being droll/facetious when it credits Rayleigh for 'discovering' this -- he discovered it in the same way that Columbus discovered America.

Take in that wikipedia citation, though, and you'll be a few steps closer to understanding the fundamentals of quantum mechanics.

Recent applications in imaging here:
https://www.ncbi.nlm.nih.gov/books/NBK599190/

For the non-scientist:

https://ls.berkeley.edu/news/taking-look-inside-brains-professor-na-ji

https://communities.springernature.com/posts/a-conversation-with-na-ji

[Imagine devoting a nation's treasure to building marvels like St. Paul's to celebrate the glory of bigger things than a ruler's ego]

Thank you all for responding! I enjoyed reading your perspectives and will plan on visiting.

I agree with much of what has been said above. It's a really beautiful church, designed by one of our most famous architects, Christopher Wren. You can see a lot of his churches and those of his apprentice, Nicholas Hawksmoor, around London, some of which are left in a state of ruin after the Blitz. In addition to what's been mentioned, you can also climb all the way to the top (if you don't mind some rickety stairs) and get great views from outside at the top of the dome.

What is a "must see" is a personal thing, that fits into our personal interests. I couldn't care less about Paris or Rome and I don't need to convince anyone to love the places I want to see -- I don't expect anyone to share my passion for IronBridge.

For me there is just the history of and the people tied to St Paul's. There's the first time I ever heard of St Paul's was when mom made 10 year old me get up really early in the morning to watch on tv the wedding of Prince Charles and Lady Diana Spencer (yuk girly things). I think the 8 site lines to St Paul's are pretty cool. It is the center of London to me, my favorite part of the city and It's where I like to stay when I am in London.