Gryffindor Common Room Chapter 6:

Elizaveta might've been too exhausted by the day's events and done sleepy by the good food to have noticed the Gryffindor Common Room, but Jorge wasn't.

At the end of a long corridor, after having walked up a great many staircases (some of which moved) was a portrait. The portrait, like the rest of the portraits at Hogwarts, and indeed, in the Wizarding World, was a moving one, and it was the portrait of a portly woman. To that portrait they went, and there they stopped. Jorge could see that the woman's lips moved, but he was too far away to hear what she said, as he'd lagged. He joined the others in time to hear the male Prefect say,

'Draco corde!'

The woman nodded regally, and to Jorge's great amazement, the portrait swung open revealing a hole in the wall.

They scrambled through it, or in Elizaveta's case, jumped sleepily, and was soon standing in a circular large room.

'Now if you would all just pay attention this way…', the male Perfect started to say before it became abruptly clear that no one was listening to him. They were all staring awestruck at the Common Room they were finding themselves in. It was a round room which were full of armchairs that looked rather squashy, some sofas, a great fireplace with a few "G" banners hanging from the mantle and a tapestry of a lion, overall; rather cosy.

The female Prefect then took two fingers into her mouth and whistled loudly.

'Oi! Listen up you!'

'Thank you, Wang. My name's Danilo Mortensen, this is Mei Wang, whom you will refer to as Wang. We're your Prefects this year. The boys' dormitory is up to the right, the girls' up to the left. You'll find bathrooms connected to your respected dormitories and your dormitory is marked with a plaque over the door stating, "First-Year".

So up a spiral staircase they went, and into another round room with five beds of the four-posters kind which were hung with deep-red velvet curtains, their trunks already having been brought up.

Jorge didn't go to sleep right away.

He lay sleepily awake and thought about the train ride here, the Sorting, the Common Room, the dorm room with the beds and would tomorrow bring ...

And with these thoughts swimming in his mind, he fell asleep.

Author's notes:

Draco corde = dragon heart (latin)

Now I can't remember if there ever was said anything about bathrooms within the Gryffindor Tower, but seeing as how people would've to break curfew in the middle of the night if they needed a potty break at that time, I think it's only reasonable to assume that there's a bathroom or two there.

In the next chapter:

Other students noticed the Common Rooms of the other Houses.

Down in the basement it was Antonio whom had been abuzz with nervous energy ever since he'd been Sorted into Hufflepuff.

[...]

The last comment was met with laughter and an agreeing murmur.

Before he went upstairs, Antonio caught a glimpse of the portrait hanging over the wooden mantelpiece;