Places
Anywhere can be a mark.
The Eiffel Tower, and the giant ketchup bottle in Collinsville, Illinois. Stand where it stands, and it's yours to take.
Photos: Wikimedia Commons and Flickr contributors, CC BY / BY-SA / CC0 / public domain · Photo credits
Not one per city
Every town has hundreds.
A fountain in Paris, a phone box in the UK, the little green man in Berlin, a tram in Lisbon. Every street has its own, and the one on your corner counts as much as the one on the postcard.
A fountain, Paris 
A phone box, UK 
The green man, Berlin 
Tram 28, Lisbon 
Tiles, Porto 
Mafalda, Lima
See one up close
Three place marks, start to finish
Find the ones near you.
The app shows the place marks around you.