Getting to the Prudential building / Skywalk Observatory

From the Prudential stop on the green line (E)

When exiting the subway area, turn left and go up escalators.
At the top, stay to the right, remain inside building, go up more escalators.
You should now be under a massive glass roof. The observatory is at the top of the building in the back.
Walk until finding a vertex in the corridor graph.
On the left is the entrance to the Prudential Arade.
Walk through and the entrance to the Skywalk Observatory should now be visible.

From the Back Bay stop on the orange line

Coming from SoCG, be near the front of the train. Coming from NEU, be near the back. Exit subway area near Amtrak station, along with most of the crowd.
Exit onto Dartmouth street, turn right, walk until Eastern Bank and cross Dartmouth.
Enter the glass building in front of some metal horses. (notice Prudential peeking above the glass)
Go up two escalators, walk through the mall, down escalators at the end, past a Starbucks, and into a "skybridge" passage over a street.
At the end of the passage you should be at the Back Bay Arcade. Walk through until you reach a vertex in the corridor graph.
Look for the Prudential Arcade, enter, and you'll be facing the entrance to the Skywalk Observatory.

Walking from SoCG

Follow Kneeland and then Stuart street until Dartmouth near the Back Bay station. Then you can follow the orange line instructions, or keep walking until you see the pedestrian "skybridge" over you. Enter underneath it on the right side of the street (next to a California Pizza restaurant) and continue with orange line instructions starting at the Back Bay Arcade.

Walking from NEU

It should be easy to find the Prudential gren line stop. Follow instructions from there.