In the later part of the Third Age, Gondor's borders were the sea to the south, the Mountains of Shadow in the east, and the White Mountains in the north; in earlier times Gondor had reached further north.
Gondor was divided into about a dozen regions. Ithilien lay in the east, between the Anduin in the west and the Mountains of Shadow in the east. Anórien was the small land north of the White Mountains, between the Anduin in the east and the land Rohan in the west. Calenardhon was the land north of the White Mountains, between the Emyn Muil and the Misty Mountains. Calenardhon was later depopulated by plagues, and was given to the Rohirrim in the 26th century T.A., after which it became known as Rohan. Enedwaith was a region northwest of the White Mountains, which was mostly abandoned in the later part of the Third Age. Between the coast and the White Mountains lay several regions, from the west to the Anduin in the east. Along the coast were the regions Anfalas, Belfalas, Dor-en-Ernil, Lebennin, and Lossarnach. Along the Mountains in the north lay the Morthond Vale, Lamedon, and the Ringló Vale. Southeast of the Anduin river-delta was the region South Gondor.
The city Osgiliath, built to the sides and over the river Anduin, was the old capital of Gondor. East of Osgiliath was Isildur's city Minas Ithil, later Minas Morgul, and to the west was Anárion's city Minas Anor on the side of the Mindolluin, the later Minas Tirith. Minas Tirith was surrounded by the Pelennor Fields, which was later surrounded by the great wall of Rammas Echor.
Gondor was founded in the year 3320 of the Second Age by Elendil's sons Isildur and Anárion after they fled the Fall of Númenor. They founded the capital Osgiliath together, while Isildur founded the city Minas Ithil to the east, and his brother Anárion founded the city Minas Anor to the west. Osgiliath later fell into decline, ravaged by plague, civil war and attacks from the east. In T.A. 1640, Minas Anor became capital. About that time Minas Itil was taken by the Nazgûl, after which it became known as Minas Morgul. In response Minas Anor was renamed Minas Tirith, the "Tower of Guard".
After T.A. 2050, Gondor was ruled ruled by the Stewards of Gondor, in the King's stead. The last ruling Steward Denethor II, in office during the War of the Ring, went insane and killed himself. After his death, command fell to Prince Imrahil of Dol Amroth for a short time. In T.A. 3019 Aragorn of the Dúnedain was crowned as King Elessar Telcontar of the Reunited Kingdom of Arnor and Gondor.