Dungeons & RequirementsFollow

This is a nice little list of dungeon levels/requirements that was originally posted on Blue Gartr by Ratatapa. I edited some of the areas to be more specific.

Sastasha -- Western La Noscea (Lv. 15)
How to Unlock : Story

Tam-Tara Deepcroft -- Central Shroud (Lv. 16)
How to Unlock : Story

Copperbell Mines -- Western Thanalan (Lv. 17)
How to Unlock : Story

Halatali -- Eastern Thanalan (Lv. 20)
How to Unlock : Talk to the NPC outside of the Walking Sands in Vesper Bay

The Thousand Maws of Totorak -- South Shroud (Lv. 24)
How to Unlock : Story

Haukke's Manor -- Central Shroud (Lv. 28)
How to Unlock : Story

Brayflox's Longstop -- Eastern La Noscea (Lv. 32)
How to Unlock : Story

The Sunken Temple of Qarn -- Southern Thanalan (Lv. 35)
How to Unlock : Talk to Nedrick Ironheart outside of the Walking Sands in Vesper Bay

Cutter's Cry -- Central Thanalan (Lv. 35-38)
How to Unlock : Talk to Silbold in Ul'dah Market Wards

The Stone Vigil (Lv. 41-44)
How to Unlock : Story

Dzemael Darkhold -- Coerthas (Lv. 41-44)
How to unlock : Level 41 - quest by your grandcompany (GC), should be at left or right side. The observatory in Coerthas south of Dragonbone by Mor'Dhona entrance

The Wanderer's Palace (Lv. 50)
How to Unlock : Talk to the NPC near Waking Sands / Allene (Vesper Bay)

The Aurum Vale -- Coerthas (Lv. 47-50)
How to Unlock : Talk to Nedrick Ironheart outside of Waking Sands