Karl Ruppert and John H. Denison visited Calakmul in 1932 as part of the First Campeche Expedition sponsored by the Carnegie Institution. They report:
"Room 2 has an average width of 1.30 m. at the floor level. The walls slope slightly inward so that at the spring line, 2.50 m. above the floor, the room is 1.20 m. wide. At the time the First Campeche Expedition visited Calakmul there was a trench in the floor, at the west end of the room, 70 cm. deep and 80 cm. long, which showed only one well-finished floor, beneath which the hearting is very compact. We were told by his guide that Lundell made the trench when he visited the site in 1931.
The doorway in the west wall, which comes in at an angle from Room 1, has an average width and height of 50 cm. and 1.30 m. respectively. The south jamb, formed by the south wall of the room, is very regular; the north jamb is uneven. Small holes, one near the base and one near the top of each jamb, perhaps allowed for the placing of poles to support and secure curtains in the doorway. The lintel is of stone. A ventilator in the west wall is shown in plate 2c.
...Approximately 30 cm. farther east [on the north wall, right side of photo] is a great crack in the masonry which extends from the floor to within 75 cm. of the top of the vault. West of the ventilator the name, "C. L. LUNDELL," with the date, "12-29-31," has been scratched in the plaster. Directly above the name are incised two connected and vertically opposed key patterns, probably ancient (fig 6b)."