Maybe you found yourself in the same situation as me when I reached the maximum level. I wanted to do lower level instances (dungeons and raids), just to pick up some nice items, and also to discover them.
But it is not necessarily always very easy to find the entries of these instances, it took me a lot of rummaging around each time to find how to get there. I therefore suggest that you explore in my company all these instances and, for some, what we can collect interesting (mounts, objects, etc.).
Direction therefore classic WoW, with all the old instances.
General maps
dungeons
1. Ragefire chasms
The entrance to this instance is in Orgrimmar, the Horde capital in Kalimdor, in the Durotar area. To get there, go right in the middle of the city.
You will find a cave, the entrance to which is dotted with purple clouds.
The gate is just to the left as you enter.
Booty : nothing interesting
2. Mortemines
Go to the Western Marches, south of Moonrun:
There you will find a large building, like a barn, with a small entrance to the side. The entrance to the keep is located in the building, at the bottom of a mine.
Booty :
- Normal: nothing interesting
- Heroic:
- Bouquet of red roses (during the Love in the Air event)
- Bouquet of ebony roses (during the Love in the Air event)
- Red Winter Hat (during the Winter Veil event)
3. Cave of Wailing
Zone Tarides du Nord, in Kalimdor.
Entrance to a stone cave:
Booty : nothing interesting.
4. Shadowfang Dungeon
In the Silverpine Forest in the Eastern Kingdoms.
The entrance is very easy:
Booty :
- Normal: nothing interesting
- Heroic:
- Bouquet of ebony roses (during the Love in the Air event)
- Green Winter Hat (during the Winter Veil event)
- Bouquet of red roses (during the Love in the Air event)
5. Blackfathom Depths
In Kalimdor, in the area of Ashenvale.
The entrance is at the bottom of the pool, then just follow the path on the minimap.
Booty : nothing interesting.
6. The Prison
In Stormwind City in the Eastern Kingdoms, Elwynn Forest.
The entrance is located in the fort north of the Mages district.
Booty : nothing interesting.
Bead the Tranchebauge
Kalimdor, Barrens area.
Far south of the area, below giant brambles.
Booty : nothing interesting.
8. Gnomeregan
In the Eastern Kingdoms, Dun Morogh area
Entrance clearly visible:
Booty :
- Normal:
- Diagram: smoldering
- Schematic: Bombinette
9. Tranchebauge Defilements
Kalimdor, Southern Barrens / Thousand Needles
The easiest way is to go south of the Barrens and rush into the bramble forest.
Then just follow the path of brambles to find the entrance to the dungeon.
Booty : nothing interesting.
10. Scarlet Monastery / Scarlet Halls
Eastern Kingdoms, Tirisfal Glades area
On the left of the monastery, just go up the stairs.
Booty : nothing interesting.
11. Uldaman
Eastern Kingdoms, Badlands
Entrance to the mine:
Booty : nothing interesting.
12. Zul'Farrak
Kalimdor, Tanaris
Entrance :
Booty : nothing interesting.
13. Maraudon
Kalimdor, Desolace
Entrance :
Booty : nothing interesting.
14. Sunken Temple
Eastern Kingdoms, Swamp of Sorrows
Entrance :
Booty : nothing interesting.
15. Blackrock Depths
Eastern Kingdoms, Burning Steppes
Entrance :
Once in the cave, the entrance is in the center, at the bottom:
Booty :
- Normal:
- Sparkling Brilliant Charm
- Most bitter dark charm
16. Bottom of Pic Rochenoire
Eastern Kingdoms, Burning Steppes
Entrance :
Same place as Blackrock Depths, but you have to take the ring on the sides to access the instance on the right. The one on the left leads to the Summit of Blackrock Peak.
Booty (Normal and Heroic):
- Worg's Crate
- Incubator egg
17. Dire Ax
Kalimdor, Féralas
Entrance : 
Booty : nothing interesting.
18. Scholomance
Eastern Kingdoms, Western Plaguelands
Entrance :
Booty :
- Heroic:
- Krastinov's Sack of Horrors
19. Stratholme
Eastern Kingdoms, Eastern Plaguelands
Entrance :
Booty (Normal and Heroic):
- Reins of the Deathcharger
Raids
20. Molten Core
Eastern Kingdoms, Burning Steppes
Entrance at the bottom of Mont Rochenoire:
An NPC right at the entrance allows you to teleport directly into the instance. Otherwise, you have to continue a little longer to find the instance entry.
Booty :
- Flame Mark
- Rune flamboyant
- Petrified Ash Core
- Hainetincelle the Tiny
21. Blackwing Lair
Eastern Kingdoms, Burning Steppes
Indicated on the map.
Booty :
- Elementium Goblin Guide
- Blackwing Banner
- Chromatic Bone Whistle
- Unharmed egg
22. Ruins of Ahn-Qiraj
Kalimdor, Silithus
Entrance: gate on the left
Booty : nothing interesting.
23. Temple d'Ahn'Qiraj
Kalimdor, Silithus
Entrance: stairs to the right
Booty :
- Viscidus globules
For all our GPS guides:
- Classic instances
- BC instances
- Instances WoTK
