The geography of Arda was initially a flat world including the continents of Aman (the Undying Lands) and Middle-earth. Aman was the home of the Valar and the Elves, separated from Middle-earth by the Great Sea, The western part of Middle-earth called Beleriand was largely destroyed and drowned after the First Age. 

Arda today is a spherical world centered around the continent of Middle-earth, which features diverse and distinct regions. 

In the far west lies Lindon, the coastal remnant of the ancient land of Beleriand, followed eastward by Eriador, home to the Shire, Rivendell, and Bree. The Misty Mountains run north to south, hosting mines like Moria and key mountain passes. East of these mountains stretches Rhovanion with vast forests like Mirkwood and Lothlórien, forests of Fangorn, and regions such as the valley of Isengard. Southward are the grasslands of Rohan and the kingdom of Gondor, bordered by the White Mountains. To the east of Gondor lies Mordor, a volcanic land ruled by Sauron, dominated by Mount Doom and Barad-dûr, its dark fortress. Beyond these locations, the lands of Rhûn and Harad extend further east and south with less detail known from Tolkien's writings. 

The Undying Lands, is a large, blessed continent west of Middle-earth, separated by the Great Sea. It is home to the immortal Valar and the Elves and is characterized by lush forests, beautiful coastlines, and the towering Pelóri Mountains, whose highest peak is Taniquetil. The coastal region, Eldamar, has the Elven city of Alqualondë with pearl-built mansions and natural harbors. The land is timeless and sacred, free from death and decay. Since the world was reshaped into a sphere, Aman is no longer physically reachable by mortals, only accessible to Elves and special beings.