(CNN)With more than 1,000 UNESCO World Heritage Sites out there waiting to be explored, most travelers can claim to having seen at least a couple of them, whether it's the Great Pyramids of Egypt, Venice, Italy, or the Grand Canyon in Arizona.
Mr. UNESCO: Meet the world's ultimate checklist traveler
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Few have seen as many as Gary Arndt.
It's been nearly eight years since the founder of travel blog Everything-everywhere.com sold his house to hit the road as a full-time traveler.
Since then, the Wisconsin native has been to 291 UNESCO World Heritage Sites -- a feat achieved by visiting all seven continents, more than 170 countries and territories, every state and territory in the United States, every Canadian province and every Australian state.
Now a well-known fixture in the travel blogging world, Arndt made a name for himself by capturing award-winning photos of his journeys -- he says he learned to shoot on his own through trial and error -- with World Heritage Sites being a particular area of expertise.
Originally, however, visiting so many UNESCO-listed sites wasn't on his mind when he set out to see the world in March 2007.
"I'm not even sure I was aware of the list until after I had been to Volcanoes National Park [Hawaii], which is what I list as my first World Heritage Site visit," he says.
"After a few months traveling, I was heading to New Zealand and I was aware that they had two sites on the list, so I made it a point to visit them.
"I then went way out of my way to visit East Rennell in the Solomon Islands, which is one of the least visited World Heritage Sites in the world."
It was at this point that he decided he'd try to make a meaningful visit to as many of the sites he could and document them for his readers.
He now has a dedicated page on which he maps his visits, with each link featuring a writeup and photo of the site.
"The ones that really stand out are the ones that aren't very well known, but should be," says Arndt.
"I visited Nahanni National Park in Canada last year, which was really amazing. It was one of the first 12 World Heritage Sites listed back in 1978, yet few people know about it.
"It's one of the greatest national parks in the world.
"Purnululu National Park in Western Australia and Mulu National Park in Borneo also fall into that category."
"Of the many World Heritage Sites I've visited, I've had the biggest surprises visiting the industrial-themed sites," he says in his post about his visit to the aqueduct.
"They don't get the same amount of attention as the ancient sites do, but they are just as important to the development of the modern world."
With 1,007 World Heritage Sites around the world, there are bound to be a few duds.
Arndt says about one in 10 are letdowns.
"Many archeology and paleontology sites are often disappointing, because the things that made them famous have been dug out of the ground and are now in museums."
He says he also questions how important some sites really are, such as the White City of Tel Aviv.
"It is by far the most ambitious World Heritage site I've visited," he says on his blog post about the Israeli site, which UNESCO calls an outstanding example of the innovative town-planning ideas of the first part of the 20th century.
"There is nothing which jumps out at you. There is no one single building or even collection of buildings that says 'this is what we are talking about.'"
He adds that Holasovice in the Czech Republic was probably his shortest visit as he "had no idea what to see or why the site was there."
"The most recent disappointment was the Vredefort Dome in South Africa," he says.
"There was no visitor center, no park and almost nothing in the way of signs."
Overall, however, Arndt says the visits have been rewarding.
"Thankfully there are far more hidden gems than there are duds," he says.
Visiting so many UNESCO-designated sites has increased Arndt's awareness of the program's importance, however, he says it's also given him insight into the flaws in the system.
"There is a lot of politics and money in play," he says.
"Rich countries tend to have more World Heritage Sites. Also, as the obvious places have been put on the list -- Great Wall, Grand Canyon, Pyramids, etc. -- ever more marginal sites have been added."
This means that with more than 20 new sites added every year, many countries are trying to add places in the belief that they'll attract more tourism dollars, says Arndt.
"With so many sites now, I think they have diluted the World Heritage brand to some extent. I think it might be worth considering limiting the number of new sites to only 10 per year, with a focus on those most deserving or in need of protection, not just putting yet another medieval European village on the list."
Though getting to all 1,007 sites will be a challenge -- particularly given some are in war-ravaged areas such as Syria -- Arndt is optimistic it won't take long before he hits at least half.
"Getting to 50% is very doable as there are many in Western Europe I still haven't visited," he says.
"I have yet to visit the majority in France, Italy, Spain, Portugal, Sweden, Norway, Finland, Switzerland and Austria. There are also many in Mexico I haven't been to."
Arndt figures if he took three to four months and had a car, he could probably reach well more than 100 sites in Europe.
"It has been a plan of mine for a while, but I just haven't gotten around to it."
So the big question is, how does someone support all that travel?
Arndt says once he decided he wanted to travel around the world it took a couple years to tie up loose ends.
For the first few years he says he paid for everything himself -- "I thought I'd be traveling for a year or maybe two" -- using money he made from selling his house and business.
These days, he says he earns money from his blog, which gets about 100,000 visits a month, and is offered opportunities for trips sponsored by tourism boards from different countries.
Arndt recently visited Finland, where he hit his 291st World Heritage Site: The Fortress of Suomenlinna, the only World Heritage Site in Helsinki.
He's now in Alberta to do some winter photography in Canada's Banff and Jasper National Parks.
"Then I'll be driving around Florida to visit some U.S. national parks before heading to Haiti.
"Given the new regulations in the U.S., I might also fly to Cuba to document some of the World Heritage Sites there.
"I will be back in Europe in the spring, then in the Galapagos Islands in September and finally in Bangkok in October."