The Doctor and Susan landed on the planet of Kwansas.
"Why did you bring us here, Grandfather" said Susan. The planet was drab. There were no plants in sight, and the ground was just full of brown, dusty rock. If Susan wasn't being polite, she would have said it was the most boring place she'd seen. And she'd seen a lot of boring places, as a Gallifreyan student.
"Just wait," said the Doctor quizzically.
"Is there trouble?" said Susan. The sky was black, and she was starting to wonder whether she should have worn something warmer.
"No trouble, child. Quite the opposite—we're alone on this planet," said the Doctor, with a smile on his face. He took out a watch, and nodded, apparently to himself. "Be patient a little longer."
And she waited. And then waited some more. Eventually, it got to the point where propriety wasn't going to stop her from complaining. "Grandfather, I-"
Then she noticed color crawling into the sky.
Red, mixed with blue, mixed with green. The colors mixed and mingled with each other to create a tapestry. It was like what she would later in life call an aurora borealis, only ten times as bright. And then she noticed something else about the colors.
"They're forming characters!" she said with glee.
"Indeed, child," said the Doctor. "You see, history's events are etched in time. This planet is unremarkable, except for the fact that it is right on a 4-Dimensional rip in the time-space continuum. Not enough to cause damage, but enough to occasionally cause effects in our universe. More specifically, every so often, the etchimgs of the events show themselves in the sky above. These are events from other universes—displayed like a hologram. "
Susan saw dragons fighting knights; eight legged creatures having marriages; creatures made of glass playing with their young; an old man with two other children fighting giant lizards with water cannons, and other sights the Time Lords would have declared impossible. And her Time Lord senses could feel the different time-lines being filtered through, and sorted into a beautiful painting made of light.
As Susan marveled at these sights, the Doctor said "See, my dear, this is why you should listen when your grandfather asks you to be patient. Look at this marvelous sight. I can't imagine why you keep on bugging me to take you to visit Earth, there's nothing so interesting in that planet." He paused, then said quietly,"Ever since reading about this place, I always wanted to take your parents here when they were young, but the Time Lords frown on so-called "silly excursions"... well anyway, it's almost over. Only happens once every millennium, you know."
Susan heard him, but as mostly looking at the shimmering lights. As it receded back into the sky, she thought she saw a girl who looked at lot like her, staring back. She blinked, and the image was gone. "That was marvelous, grandfather," she said, as the sky returned to pitch darkness.
"Isn't it beautiful?" said the Doctor, clapping in delight.
Susan hugged him, and said " Thank you, grandfather. I won't ever forget it."