Time travel media tends to have trouble finding new ways for their characters to travel, but Doctor Who found an odd method of transportation with the use of a TARDIS, a ship that looks like an ordinary 1960s British police box from the outside, but the inside is an endless pocket universe with an ever-changing display. This allows the writers to include any room needed, with only a few becoming standard rooms, as seen in Series 7, Episode 10, "Journey to the Centre of the TARDIS." This is a bottleneck episode that exists entirely in the endless TARDIS, and it reveals seven rooms within the TARDIS that hold importance to The Doctor and the series as a whole.
The Console Room
This is the main room within the TARDIS and the very first place one enters. It's also the most heavily featured place within the entire series, but its appearance changes many times. There have been countless different console rooms, with each Doctor having at least one, but there are a few who have two or more, with a new console room set to be revealed in the Doctor Who New Year's special "Revolution of the Daleks."
The Library
As a person who once said, "Books, the most powerful weapons in the universe," it is unsurprising that The Doctor has a library of their own. While very little is seen of it, it does look massive and endless, similar to The Library in Series 4's "Silence in the Library." Within this library is a book detailing the events of the Time War written by its only survivor, The Doctor. This book also holds the greatest secret in the universe, The Doctor's real name, which Clara discovered but ultimately forgot when time reset itself.
Architecture Reconfiguration System
This is one of the most important rooms within the TARDIS. It is responsible for creating any and all technology needed to help The Doctor in their adventures and missions. The room looks like a tree with spheres hanging from the branches. It is also the room responsible for the constant redesigns of the TARDIS and the sonic screwdriver.
Eye of Harmony
This room holds an exploding star in the midst of becoming a black hole, which was ripped from its orbit and suspended in a permanent state of decay beside the heart of the TARDIS. Time Lord engineering found a way to make this possible and use that energy to power up the most powerful ship in the universe. Therefore, entering the room is so dangerous that it is only accessible for one minute before it boils one's blood and melts their skin.
The Observatory
This is a simple and small room with only a large telescope within it. While never mentioned before or since, this is a nice room that does not need to be in a ship. For instance, the TARDIS is capable of getting close to the surface of the sun without getting a scratch or scorch mark, so having a telescope seems redundant. Regardless, it is a fun side room to see.
The Pool
This is the infamous pool that kept coming up in Series 5, and it finally makes its first appearance in Series 7 with this episode. This is the same pool that River Song dove into while escaping Dalton during the Silence invasion, and it's the one that the 11th Doctor climbs up from when he first crash lands in Amy Pond's backyard.
The Engine Room
In short, this is the heart of the TARDIS. While it is imagined to be epic, audiences were unable to see it as the engine exploded in Series 5. As it exploded, the TARDIS wrapped its hands around the heart, freezing it so it would keep The Doctor safe. Therefore, the engine room in this state is a blank void with pieces of metal floating around in stasis.