Senju Grand Tree.
The Senju Grand Tree is the home of Uetto Senju and also the HQ for the Senju Clan leaders. Within it lives Uetto Senju who, along with other leaders, generally hold meetings there. It is found within the training grounds of Konoha and is sentient so that it can rebuild itself and find a new leader if the current leader cannot. The tree can also be moved by merging with the ground after one who is able to performs neccesary seal. Not only that, but the roots of the tree span throughout Konoha when it is summoned there.
First Floor
The first floor -- the floor people are greeted with after entering the tree after entering it via the door at the base of the tree -- is a long hallway that holds nothing of notice aside from a game room, restroom, and kitchen.
Second Floor
The second floor holds naught but a giant oval table and chairs. This floor is used for meetings with the chairs which are usually conducted via the Magic Lantern Body Technique .
Third Floor
The third floor houses the Senju Grand Library which is stocked with books and scrolls of almost all the jutsu in the world. It also holds information that people of the Senju clan have come across such as seals, techniques unique to few Shinobi, and Kekkei Genkai .
Fourth Floor-Sixth Floor
These floors hold training rooms for, well, training. They are just large rooms for members an leaders alike to train in.
Seventh Floor
The seventh floor is a gym stocked full of training equipment and the like.
Eight Floor
The eigth floor contains many rooms filled with beds. These are, of course, sleeping quarters for members or whoever is staying in the tree at the time.
Ninth Floor
This floor holds 'unique' items that Uetto has such scrolls containing certain jutsu.
Tenth Floor
The tenth floor is where Uetto himself and sleeps but it also houses another room where white Mokuton clones dangle from the celling of the tree. The second room also contains various weapons and a place where Uetto conducts experiments.