onent of the university theory pointed these out as
just what might be found in classrooms. There were escalators, up and
down, on either side of the hall, and more on the intersecting passage
to the right.

"That's how they handled the students, between classes," Martha
commented. "And I'll bet there are more ahead, there."

They came to a stop where the hallway ended at a great square central
hall. There were elevators, there, on two of the sides, and four
escalators, still usable as stairways. But it was the walls, and the
paintings on them, that brought them up short and staring.

They were clouded with dirt--she was trying to imagine what they must
have looked like originally, and at the same time estimating the labor
that would be involved in cleaning them--but they were still
distinguishable, as was the word, _Darfhulva_, in golden letters above
each of the four sides. It was a moment before she realized, from the
murals, that she had at last found a meaningful Martian word. They were
a vast historical panorama, clockwise around the room. A group of
skin-clad savages squatting around a fire. Hunters with bows and spears,
carrying a carcass of an animal slightly like a pig. Nomads riding
long-legged, graceful mounts like hornless deer. Peasants sowing and
reaping; mud-walled hut villages, and cities; processions of priests and
warriors; battles with swords and bows, and with cannon and muskets;
galleys, and ships with sails, and ships without visible means of
propulsion, and aircraft. Changing costumes and weapons and machines
and styles of architecture. A richly fertile landscape, gradually
merging into barren deserts and bushlands--the time of the great
planet-wide drought. The Canal Builders--men with machines recognizable
as steam-shovels and derricks, digging and quarrying and driving across
the empty plains with aqueducts. More cities--seaports on the shrinking
oceans; dwindling, half-deserted cities; an abandoned city, with four
tiny humanoid figures and a thing like a combat-car in the middle of a
brush-grown plaza, they and their vehicle dwarfed by the huge lifeless
buildings around them. She had not the least doubt; _Darfhulva_ was
History.

"Wonderful!" von Ohlmhorst was saying. "The entire history of this race.
Why, if the painter depicted appropriate costumes and weapons and
machines for each period, and got the architecture right, we can break
the history of this planet into eras and periods and