by Tom Buehler, Benjamin Monreal, and Greg Pliska
Problem: Holi Town/​Patriots’ Day Town

The first step of the puzzle involves identifying several images from locations on the MIT campus while tracing paths that visit those locations. Solvers familiar with the campus may be able to trace some of the paths remotely; others will need to do the actual walkaround. Some locations may require an MIT ID to access, but even without access the route can be reconstructed from later clues, or traced using a map.

Each image has a blacked-out word on it. Again, some of these can be intuited or identified; others will require visiting the location in question.

The blacked-out words are:

  1. HEAD
  4. RAY
  8. CONE
  10. VALERA
  11. 204
  12. 206
  13. BABY
  14. 1973

Here are the seven MIT routes, explained, with the blacked-out words included. (Colors refer to map below.)

  • red Start at 38-401 and find HEAD. Go down the stairs, walk between 34 and 24.
  • Walk down the driveway between 24 and 26 towards 12. Enter 26 via the cutaway.
  • Turn right into 12 and then exit into the courtyard between 12 and 8.
  • Walks towards the dome and enter 4 at the basement level.
  • Go up the stairs to the infinite and find the MIT SHAKESPEARE Ensemble poster. Walk down the Infinite and enter 11. Go through it and exit onto the driveway between 11 and 13.
  • Head north and stop at Vassar St.
  • orange Start in 14N and find INTREPID on the poster. Exit the building and walk until you reach Ames St. Follow Ames to the crosswalk and enter 66. Walk to 56, exit, and walk towards 32 to find RAY.
  • Enter 32 and exit at the Gates entrance near the Kapoor sculpture.
  • Walk to Vassar and Main, then turn left and walk beside 76.
  • Cross Ames and enter E19 to find HADLEY and stop.
  • yellow Start in lobby 37 and find CHALLENGER.
  • Go to 35, then 33, find DOUBLE, then 9, then 13.
  • Stop at the connecting corridor halfway through 13 and go back.
  • Go to Lobby 7, then 3, and stop at the mural of the group of people.
  • green Start on the second floor of 2 and find CONE.
  • Head north until you reach the driveway between 26 and 36.
  • Follow the driveway to the nearest entrance of 24. Continue to the garage door of 24.
  • Walk to the entrance of 13, then the nearest (back) entrance of 37.
  • Enter 37, go the the second floor, find SURVEYOR, then exit 37 at the other end.
  • Turn left and follow Mass. Ave. until you reach 1 and stop.
  • blue Start at the entrance to Hayden. Go to the basement and find VALERA.
  • Go up the stairs at the other end of the basement and walk back through the library and out where you came in.
  • Now go to the Lewis Music Library and walk to the southwest corner.
  • indigo Start at 8-204. Walk to 4, to 2, to 6, then stop at 8-206.
  • violet Start at the bike cage by Maseeh. Walk into the Student Center and find BABY in LaVerde’s.
  • Exit the Student Center, walk through the park where Bexley once was, and cross Mass Ave at Amherst St.
  • Enter 1, go to the second floor, and find 1973 on the School of Engineering posters.
  • Go back the way you came and through 5 and then to 7.

When drawn on an MIT campus map, these routes spell, in order, the phrase USE MOON.

Solvers can then plug the values for numbers 1-14 into the next set of descriptions and “use moon”—uniquely identify segments of lunar excursions from various missions, including Apollo 11 & 12, Apollo 14-17, Lunokhod 1 & 2, and Chang’e 3.
Lunar Excursion Description (numbered words in CAPS)src missionletter shapemoon site
From INTREPID 200m to SURVEYOR siteApollo 12east-southOceanus Procellarum
200m of path closest to HEADApollo 12west-southOceanus Procellarum
Return from Station 10 near HADLEYApollo 15eastHadley-Apennine
First ~1.3 km, January 1973Lunokhod 2southeastLe Monnier
2nd ~1.3 km, February 1973Lunokhod 2southLe Monnier
From flagpole, approach DOUBLE and follow footpath until north of its east edgeApollo 11descending C-shapeMare Tranquillitatis
First 0.5 km past VALERALunokhod 1northeastMare Imbrium
Waypoint 204 to Waypoint 206, 13-14 Jan 2014Chang’e 3west, then hook nMare Imbrium
75 yards on either side of point of closest approach to CONEApollo 14NE and SWFra Mauro
From due south of Station 9, in direction of BABY RAY, to Station 9 itselfApollo 16ascending C-shapeDescartes Highlands
From 1 km north of CHALLENGER to point due north of SHAKESPEAREApollo 17north and eastTaurus-Littrow

The flavortext mentions Braille as a hint to other alphabets for the blind. In this case, solvers want to heed the instruction USE MOON in a different way, using the Moon System of Embossed Reading, or Moon Type, to read the paths on the lunar surface. (See Moon type key to the right.)

The eleven lunar paths are mapped below, along with their Moon-to-Roman alphabet decodings.

  1. From INTREPID (lunar module landing site, marked by X) 200m to SURVEYOR site. [M]
  2. 200m of path closest to HEAD. [E]
  3. Return (to landing site) from Station 10 near HADLEY. [T]
  4. First ~1.3 km, January 1973 [R]
  5. 2nd ~1.3 km, February 1973 [I]
  6. From flagpole, approach DOUBLE and follow footpath until north of its east edge. [C]
  7. First 0.5 km past VALERA [S]
  8. Waypoint 204 to Waypoint 206, 13-14 Jan 2014 [P]
  9. 75 yards on either side of point of closest approach to CONE [A]
  10. From due south of Station 9, in direction of BABY RAY, to Station 9 itself [C]
  11. From 1 km north of CHALLENGER to point due north of SHAKESPEARE [E]

This spells the answer to the puzzle, METRIC SPACE.