12
The house adress is : 12 Grimmauld Place, London
He inherits Sirius Black's house - Grimmauld Place and his house elf, Kreacher.
Sirius's house, Grimmauld Place.
It is often referred to as The House of Black, or Headquarters (for the order). Also Grimmauld Place.
Harry Potter inherited it from Sirius Black.
He lives in number 12, Grimmauld Place with the Order of the Phoenix
You meant where they met? In HP5, they met at Number twelve , Grimmauld Place , which is the Black's house for generations. In HP6 , there was nothing about the Order but Harry (who recently inherited Grimmauld Place from Sirius) insisted that it was kept as Headquaters. In HP7 , Number twelve , Grimmauld Place was Headquaters. But when Hermione gave the secert to Yaxely , it wasn't Headquaters anymore. The Burrow was. But when Lord Voldemort took over the Ministry , Shell Cottage , where Bill and Fleur lived , became Headquaters ever since.
12 Grimmauld Place
He lives in number 12, Grimmauld Place with the Order of the Phoenix
The Clue for Day Five was: What is the house number of the Headquarters for the Order of the Phoenix in Grimmauld Place?
He stays at number Four, Privet Drive and he later gets taken to number Twelve, Grimmauld Place.
Everything Sirus owns--Number 12 Grimmauld Place (and everything that is in it), and Kreacher (Sirius's house-elf.)