What is a visit to Greenwich without a photo op at the Prime Meridian? Most other tourists wondered the same thing because a massive queue of people were waiting to take their photo on this famous market in the Greenwich Royal Observatory. I thought there had to be another demarcated segment (and way to get the photo op without paying). And happily, my hunch turned out to be right.
I strolled down the hill and found a vertical Prime Meridian line on a wall. Although it was free, there was still another relatively large line of visitors. But a frantic smartphone search brought me to wonderfully helpful advice from Otts World. After a walk through the park, I got to sit on the famous 0 degree longitude line for $0 and 0 wait. Success!