Yeah, the Western Wall actually fits into your definition perfectly. I am mildly insulted (“mildly” because I don’t think you actually meant to imply this) by your insinuation that the holiest spot in Judaism isn’t in “active use”.
ETA: OTOH, the Tower of London actually IS “set aside and roped off”.
The same thing could be said about St Peter’s or various sites in Israel of significance to Christians, and I wouldn’t hold it against anyone. They’re not “roped off” it’s true, but once a historic or religious site achieves worldwide significance and attracts a steady stream of both religious pilgrims and secular tourists, and has done so for hundreds or thousands of years, then one would be more surprised by the absence of graffiti rather than the reverse, because the traffic of visitors has been so heavy for so long.
I can’t match the age of the graffiti in the OP, but there is one which has meaning to me. Near our city’s biggest lake (it’s artificial - something which many accuse the whole city as being) there a piece of the pavement which says “Sex Pistols”. I first saw it in 1984, but I would guess it originated in the late '70s.
The thing is, that piece of pavement is on the route of the annual 10K “Canberra Times Fun Run” (the largest community run in our city). Every year for the last 26 years I have run over the graffiti. To me the Sex Pistols now mean, “only about one and a half K to go.”
The Cow and Calf rocks at Ilkley is well known for its grafitti.
http://www.fotothing.com/photos/d08/d0841499dd4afde35e00a8133a74e746_313.jpg
http://www.fotothing.com/photos/797/7973bde4b17ebba38dec6be078cc8a76_ae8.jpg
My grandfather built a house for his wife and daughter (my mom) in the late 1940s from a surplus Quonset hut. I never saw it myself, but my mom tells me he preserved some of the graffiti -mostly nude women - that the soldiers had drawn on a wall which became the back of a closet. My grandmother was not especially amused, but she let it be. They sold the house 20 years ago and I have no idea if the current owners painted it over or not. Would be cool if it were still there.
Well before sidewalks, tourists came to climb Stone Mountain, a large granite monadnock just east of Atlanta, GA.
Some folks had the presence of mind to bring hammers and chisels to immortalize their visit; you can find graffiti carvingsall along the western trail that goes to the top of the mountain. While I can’t authenticate any of them - some are clearly recent - you can tell that many of them dated in the 1800s are genuine.
Is it still allowed to resurrect zombies? If so, I have an image here of Los Angeles paving contractor’s stamp from the early 1890s. There’s no date given, but city directories from the period show that this paving company was at this address no earlier than than 1892 nor later than 1896. The address itself no longer exists,nor does the entire New High Street except for a two block remnant in Chinatown.
For those who know L.A. this is in the Temple / Beaudry area.
Near Clark Park in west Philly, there’s a place where a large dog walked through wet cement. Every time I see it, I wonder- legend says you can become a werewolf by drinking water from a wolf’s footprint. Has this bit of cement lead to any were dogs?
Philly also has a few Toynbee Tiles. Toynbee tiles - Wikipedia
Philly’s Magic Gardens started as one man’s graffiti/vandalism/attempt to deal with a mental breakdown. Then everybody decided it was so wonderful it should be preserved.
The steps of my old home town library in South River, NJ (now the Society for Cultural and Historical Preservation and the town museum) has “B.B. July 1863” carved into the front steps. Apparently there was a Civil War battle that day that "B.B’ commemorated on that day. Or maybe it’s the day he got lucky. In any event, it’s still there (although I can’t find a picture of it in a quick search)
I spotted a Toynbee Tile, probably a copycat tile, set into the street next to the curb across the street from the northeast entrance of the Indianapolis Motor Speedway. I was there for the inaugural Grand Prix race on the then-new road course at IMS. It was a hot day, and I was heavy-laden with a cooler, a backpack and a folding chair, being nudged along by my grumbling wife. She didn’t want to stop and take a picture, so I didn’t.
Sort of similar to that is the work of Jim Bachor, who makes mosaic art to fill potholes in city streets. Here is a story from CBS News Sunday Morning about his work, with some nice photos.
When my grandmother was a toddler, there was a new sidewalk being put in outside her family’s house in Oklahoma, so my great-grandfather took her out and let her put her bare feet in the wet concrete.
A few months later, my great-grandmother died of the Spanish flu, and my great-grandfather decided to leave Oklahoma and take the baby to live with his mother in Virginia.
Fifty or sixty years after that, my grandparents were taking a road trip through Oklahoma (possibly with my great-grandfather, who would have been still alive at the time) and decided to look for Grandmom’s baby footprints in the sidewalk. And they found them!
Grandmom died four years ago at the age of 100. I wonder if her footprints are still there.
Awesome story.
In August 1957 a family of two parents and two daughters left their names and footprints in the Rancho Park neighborhood of L.A. I’d love to find these people online.
Was out yesterday exploring some somewhat remote areas south of where I live. There is some farming out there, but not a whole lot, so there is a concrete canal. I happen to look over as I was going along the canal for a short stretch and saw these.
Some of the names are partially obscured by repairs, but I wonder who they were. Workers who helped build the canal? Farm workers?
There was a story a few years back about a school installing whiteboards, and removing all the old chalkboards to do it… only to discover that the chalkboards had been installed on top of other chalkboards, something like 70 years previous, and the old chalkboards still had their last lesson written on them. Judging from the work on the boards, the installation had been done over Thanksgiving break.
Next time I go to Toronto, I’m going to have to look for them. 
I can’t find anything online about what it says but the Red Garter Inn, a 100-year-old former bordello in Williams, AZ, has preserved some original graffiti on the walls. In this room, it’s in that wide frame in the center.
Totally not within the OP parameters but I have to post this graffiti
