Rohan

Crystal Quarry.

Crystal quarry is also same as Ahkma Cave and good till level 50-55.

Traitor's Guillotine.

Traitor's Guillotine in Human town is a great place to level up until level 45.

Kai'non.

These places marked in Kai'non are also great to level up until level 45.

Limestone.

Limestone map is great all rounder leveling spots up to level 60+.

Level 65+.

There are many places to level at after you reach 65+. 
Rahkon level 2. 
Rahkon level 3. 
Rahkon level 4. 
Southern. 
Kowarre Map. 
Jubas Water Temple. 
Black Dragon Sanctuary. 
Shattered Lands in Dharvegawan. 

These maps teleport stone can be purchased from Adrian NPC located at Human/Hazy/GH!.

Level 85+.

This is the endgame of Classic. 
Rahkon level 5. 
Flame Temples. 
Ronelia Interior. 
Ronelia Exterior. 
Ronelia Dungeon. 
Hazy. 
Ruler Underground Dungeon. 

These maps teleport stone can be purchased from Adrian NPC located at Human/Hazy/GH!.