Robert E. Howard 
Jewels of Gwahlur [EPUB ebook] 

The cliffs rose sheer from the jungle, towering ramparts of stone that glinted jade-blue and dull crimson in the rising sun, and curved away and away to east and west above the waving emerald ocean of fronds and leaves. It looked insurmountable, that giant palisade with its sheer curtains of solid rock in which bits of quartz winked dazzlingly in the sunlight. But the man who was working his tedious way upward was already halfway to the top.
He came of a race of hillmen, accustomed to scaling forbidding crags, and he was a man of unusual strength and agility. His only garment was a pair of short red silk breeks, and his sandals were slung to his back, out of his way, as were his sword and dagger.