At Nine and Three Quarters

Yes, really. King's Cross Station, Platform 9 and 3/4. There is a mostly-blank wall with a little sign, plus the handle-half of a luggage trolley sticking out of the wall. Every time we looked, tourists were taking pictures of themselves "going through." We found our own way, though. (Yes, we were also tourists, and quite fine with that.)

We weren't sure we should be entering to the platform, as these trains are above-ground, but our underground passes seemed to work, so we confidently walked past several uniformed train personnel and on down Platform #9. We couldn't quite see where 10 was...two 18-year-old British boys were 2 meters  behind us. I heard one of them whisper sheepishly to the other, "Where is the spot where he goes through...?" They were there for the same reason!

Finally we figured out that 10 was on the other side of this long wall. Here is an archway near a passageway to the other side....

We didn't make it through, as you can see by Son #1 being brought up short. Is it because we are Muggles? How did Hermione do it? Ah - ask the experts. Son #1 says it is sealed up except for those two days of Hogwart's travel. That explains it.

The two teenagers were cute. They obviously were a little embarrassed about why they were there, but I completely understood. My 21-year-old has explained that her generation grew up with Harry. She read The Sorcerer's Stone around age 10 (when Harry was 11), and The Deathly Hallows came out just after she graduated from high school; a friend in town had it pre-ordered, read it in one night, and she had it the next day. He is a real person in their lives, and his world is just as real. We enjoyed being part of it for 5 minutes.