Recently I've gotten really into foursquare. Even though it's not as new as it was a few years ago, I still find the process of tagging the places I've been strangely addicting. By using a phone to keep track of restaurants, parks, and cities that I've ventured, I have a record of what I've been up to, which is quite fun to look back on. While the current digital iteration of the "check-in" is new, marking places one has been isn't a new concept, and shares a lot of the same motivations as writing graffiti.
Today I walked to the end of a long peninsula near Cape Cod, and checked in on foursquare, so that I would remember doing so down the line. Someone had beaten me to it, by almost 48 years, as attested by a block of concrete: