RUINS OF HYBORIA
Despite the name of this book*, it is truly an excellent sourcebook for your Conan game. Consider it a tool for the GM. It will help you create your own dungeon-type locations, and the book is very useful in converting 3.0/3.5 D&D and/or Pathfinder adventures for use in your game.
Here's a run-down of everything that is in this tome.
*"Hyboria" is not the correct way to refer to Conan's world. The world is not called "Hyboria". The world is our Earth, in the distant, ancient past, somewhere around 10,000 years ago. Conan lives in a time when the world looked different than it does today, though the land masses and continents are similar at this time.
This part of our non-recorded history is referred to as the "Hyborian Age," named for an ethnic tribe of barbarians, the Bori, that swept from the north and overthrew the most powerful kingdom known to exist at that time, ancient Acheron. Upon the ruins of Acheron, the Bori tribes grew and prospered, creating great, civilized kingdoms--the most powerful kingdoms during Conan's life. This is why it is said that Conan lived during the Hyborian Age--literally, the Age of the Bori.
The Bori conquering Acheron will, itself, be repeated in the future when the Gauls and other barbarians cause the the downfall of the great Roman Empire. The Bori tribes are the forefathers of the Europeans. The Bori become the Hyborians, populating the great civilized kingdoms of Conan's time--all of which have blood that still flows in the French and Germans, Spanish, and British, while other races, like the Cimmerians and the Vanir and Aesir, become the Celts and Irish, and the peoples of the north in Iceland and Norway.
Thus, to refer to Conan's world as "Hyboria" is not correct. Hyboria is not the name of the planet or even an empire or kingdom. Therefore, the correct name of this book should be: RUINS OF THE HYBORIAN AGE.
RUIN GENERATOR
The first section of the book is dedicated to creating dungeon locations. There are several lists where a GM can either pick what he wants or roll randomly to "discover" his ruin. This generator doesn't just create what the place looks like. It also creates a background for the ruin. It helps the GM brainstorm on what the original builders were like, and what the place was used for when it was built. Conan dungeons are not just adventure locations. They connect with the story and "make sense" within the bounds of that story.
CULTURES & RUINS
This chapter of the book discusses various locations of the Hyborian Age and what the ruins in that part of the world would be like. Some sample ruins are provided--most of these taken from Conan stories.
So, my current game is set in Argos, right? I read the section on Argossean ruins, and I am given two sample ruins to view: Eidoran, from Marvel graphic novel, Conan: The Skull of Set. And, the ancient Acheronian ruin of Tartarus, seen in the novel, Conan And The Grim Grey God (by Sean A. Moore), and also mentioned in Conan of the Red Brotherhood (by Leonard Carpenter).
CONAN'S RUINS
Several chapters come next, each presenting in detail, the infamous Ruins that Conan has explored. These are completely detailed locations, each recorded on several pages in the book, that you can use in your game.
City of the Winged One, from Howard's Queen of the Black Coast.
City of the Ghouls, from Howard's The Hour of the Dragon.
Dagoth Hill, from Howard's The Scarlet Citadel.
Green Stone Cities. Howard mentions this "green stone" in more than one of his stories.
Gazal, from Howard's Drums of Tombalku.
The Isle of Iron Statues, from Howard's Shadows in the Moonlight.
Isle of the Black Ones, from Howard's The Pool of the Black One.
Khet, The City of Scorpions, from John Maddox Roberts' Conan The Rogue.
Kuthchemes, from Howard's Black Colossus.
Pteion The Damned, from Poul Anderson's Conan The Rebel.
Tombs & Pyramids. Since they dominate some lands during the Hyborian Age, this covers the details.
Xuchotl, from Howard's Red Nails.
EXPLORING RUINS
This chapter has notes for the GM on placing and playing ruins in his game. Adventure ideas. Cave-ins. Large section on Traps. Treasure in a Conan game. New Feats for Tomb Raiders.
MONSTERS OF THE RUINS
This is a generation system that allows you to describe creatures suitable for the Hyborian Age. The GM can roll on or pick from tables. This will create a "picture" in your mind's eye, and once you have that, you can use the rules in the book BESTIARY OF THE HYBORIAN AGE to put stats to your creation.
This system helpful when converting standard D&D adventures for use in a Conan campaign. Players may recognize a monster from playing D&D, or the monster, as-is, may not be suitable for the Hyborian Age. You can keep the D&D stats (modified for use in the Conan RPG, of course) of a monster but use this system to describe it in a totally new and fresh way.
For example, a low level D&D adventure may have a young adult dragon in it. Well, that monster is right at home in a Forgotten Realms game, but you don't think it fits well in your Conan game. No problem. Keep the young adult dragon's stats, but use the Monster Description tables to totally re-design the look of the creature. Your players will have no idea that what they are fighting is mechanically the same as the young adult dragon. They'll believe that it is a man-shaped thing with a snake for a head because that's the way you described it!
This last section of the book also contains a Bestiary of several pages presenting monsters seen in Conan's various tales.

Despite the name of this book*, it is truly an excellent sourcebook for your Conan game. Consider it a tool for the GM. It will help you create your own dungeon-type locations, and the book is very useful in converting 3.0/3.5 D&D and/or Pathfinder adventures for use in your game.
Here's a run-down of everything that is in this tome.
*"Hyboria" is not the correct way to refer to Conan's world. The world is not called "Hyboria". The world is our Earth, in the distant, ancient past, somewhere around 10,000 years ago. Conan lives in a time when the world looked different than it does today, though the land masses and continents are similar at this time.
This part of our non-recorded history is referred to as the "Hyborian Age," named for an ethnic tribe of barbarians, the Bori, that swept from the north and overthrew the most powerful kingdom known to exist at that time, ancient Acheron. Upon the ruins of Acheron, the Bori tribes grew and prospered, creating great, civilized kingdoms--the most powerful kingdoms during Conan's life. This is why it is said that Conan lived during the Hyborian Age--literally, the Age of the Bori.
The Bori conquering Acheron will, itself, be repeated in the future when the Gauls and other barbarians cause the the downfall of the great Roman Empire. The Bori tribes are the forefathers of the Europeans. The Bori become the Hyborians, populating the great civilized kingdoms of Conan's time--all of which have blood that still flows in the French and Germans, Spanish, and British, while other races, like the Cimmerians and the Vanir and Aesir, become the Celts and Irish, and the peoples of the north in Iceland and Norway.
Thus, to refer to Conan's world as "Hyboria" is not correct. Hyboria is not the name of the planet or even an empire or kingdom. Therefore, the correct name of this book should be: RUINS OF THE HYBORIAN AGE.

RUIN GENERATOR
The first section of the book is dedicated to creating dungeon locations. There are several lists where a GM can either pick what he wants or roll randomly to "discover" his ruin. This generator doesn't just create what the place looks like. It also creates a background for the ruin. It helps the GM brainstorm on what the original builders were like, and what the place was used for when it was built. Conan dungeons are not just adventure locations. They connect with the story and "make sense" within the bounds of that story.
CULTURES & RUINS
This chapter of the book discusses various locations of the Hyborian Age and what the ruins in that part of the world would be like. Some sample ruins are provided--most of these taken from Conan stories.
So, my current game is set in Argos, right? I read the section on Argossean ruins, and I am given two sample ruins to view: Eidoran, from Marvel graphic novel, Conan: The Skull of Set. And, the ancient Acheronian ruin of Tartarus, seen in the novel, Conan And The Grim Grey God (by Sean A. Moore), and also mentioned in Conan of the Red Brotherhood (by Leonard Carpenter).
CONAN'S RUINS
Several chapters come next, each presenting in detail, the infamous Ruins that Conan has explored. These are completely detailed locations, each recorded on several pages in the book, that you can use in your game.
City of the Winged One, from Howard's Queen of the Black Coast.
City of the Ghouls, from Howard's The Hour of the Dragon.
Dagoth Hill, from Howard's The Scarlet Citadel.
Green Stone Cities. Howard mentions this "green stone" in more than one of his stories.
Gazal, from Howard's Drums of Tombalku.
The Isle of Iron Statues, from Howard's Shadows in the Moonlight.
Isle of the Black Ones, from Howard's The Pool of the Black One.
Khet, The City of Scorpions, from John Maddox Roberts' Conan The Rogue.
Kuthchemes, from Howard's Black Colossus.
Pteion The Damned, from Poul Anderson's Conan The Rebel.
Tombs & Pyramids. Since they dominate some lands during the Hyborian Age, this covers the details.
Xuchotl, from Howard's Red Nails.
EXPLORING RUINS
This chapter has notes for the GM on placing and playing ruins in his game. Adventure ideas. Cave-ins. Large section on Traps. Treasure in a Conan game. New Feats for Tomb Raiders.
MONSTERS OF THE RUINS
This is a generation system that allows you to describe creatures suitable for the Hyborian Age. The GM can roll on or pick from tables. This will create a "picture" in your mind's eye, and once you have that, you can use the rules in the book BESTIARY OF THE HYBORIAN AGE to put stats to your creation.
This system helpful when converting standard D&D adventures for use in a Conan campaign. Players may recognize a monster from playing D&D, or the monster, as-is, may not be suitable for the Hyborian Age. You can keep the D&D stats (modified for use in the Conan RPG, of course) of a monster but use this system to describe it in a totally new and fresh way.
For example, a low level D&D adventure may have a young adult dragon in it. Well, that monster is right at home in a Forgotten Realms game, but you don't think it fits well in your Conan game. No problem. Keep the young adult dragon's stats, but use the Monster Description tables to totally re-design the look of the creature. Your players will have no idea that what they are fighting is mechanically the same as the young adult dragon. They'll believe that it is a man-shaped thing with a snake for a head because that's the way you described it!
This last section of the book also contains a Bestiary of several pages presenting monsters seen in Conan's various tales.