Creeping up the side of the building

[Vladv1]

"Now, the front of the hotel sported a large fountain that was on a timerthat started it spouting at 8:00 a.m. This was too much temptation for the roadie. He lugged two containers up the stairs and poured them into the nearly empty pool of water. We awakened to a beautiful Munich day, happy and relaxed that we were going home. I opened my curtains to greet the day and gazed down upon the now non-existent fountain. Creeping up the side of the building were mounds of suds. It had spread out into the street and covered all the cars that had parked through the night".

"Rainbow In The Dark", Ronnie James Dio.

What does "creeping up the side of the building" mean in other words? What is "side" here? The floor? What does "creep up" mean here?

 

[emsr2d2]

For the umpteenth time, @Vladv1, I have removed the bold from the text that forms your question. You need to bold the relevant words only in the quote, simply to make it easier for readers to spot the relevant words in the block of text. There is no need to put them in bold anywhere else.

Do you know what "creep" (verb) means? If so, can't you work out what "creep up" means? What definitions of "side" have you seen that suggests it could mean the floor? (On a logical note, how could something creep up a floor, which is horizontal?