The Fountain Palace, also known as the Castle of Per'Agthra was the premier royal residence of the Queen Mothers who ruled the Hapes Consortium. Situated on Hapes itself, this centuries-old fortress-palace served as an ancient symbol of royal authority for the monarchy: other royal residences such as Reef Fortress were places where the Queen Mothers stayed, but Per'agthra was the home of the Hapan monarchy.
Even after Queen Mother Ta'a Chume opened the borders of the Hapes Cluster to outsiders in 8 ABY, contact was scarce, and this, coupled with traditional Hapan secrecy, may have been responsible for some uncertainty regarding the exact location of the palace. While most sources suggested that Per'Agthra stood on the crags overlooking the capital city of Ta'a Chume'Dan, New Republic Intelligence reports said that this was in fact Star Home, outwardly an exact copy of the castle, but in reality a hyperspace-capable cruiser.
Whatever the exact truth, the existence of Star Home attested to the importance of Per'Agthra to both the family of the Mothers, and the state ceremonial of Hapan political life. The Fountain Palace remained as a private residence for the court, while a second, identical castle served as a public proxy, enabling the Mothers to hold court amid the iconic towers and turrets of their ancestral seat when they visited the other worlds of the Cluster—or even, on rare diplomatic visits, foreign capitals like Coruscant.
Behind the scenes
The equation of the Fountain Palace and the Castle of Per'Agthra is based on the fact that both are said to be the models for Star Home in different sources, namely Cracken's Threat Dossier and the Wizards of the Coast online scenario Hapes: Ladies First. 
As intimated above, however, canon material disagrees on whether the real Fountain Palace or Star Home stood on the bluffs above Ta'a Chume'Dan. Cracken's Threat Dossier, presented as a series of in-universe intelligence reports, is the first source to describe the Hapan capital, and states explicitly that the city is dominated by Star Home's surface landing platform, but a number of other sources suggest otherwise:
- Hapes: Ladies First states explicitly that it is the Fountain Palace which overlooks the capital.
- The New Jedi Order: Agents of Chaos II: Jedi Eclipse describes a line of dignitaries stretching from the Lorell Hall, which is definitely on the bluffs above the city, "nearly to the grand entrance of the Fountain Palace".
- The New Jedi Order: Dark Journey places the Hapan royal palace just outside the capital.
All of these references could, technically, be explained away: the relevant passage in Ladies First is extract from another in-universe source, a swashbuckling memoir by pirate Grov Bricker; the line in Jedi Eclipse could be retconned as a hyperbolic turn of phrase, and Dark Journey does not use the names "Fountain Palace", and does not explicitly exclude the possibility that the "palace" is Star Home.
However, the apparently out-of-universe "Gamesmaster Notes" in Ladies First say that Star Home "does not have the necessary plating or shielding for atmospheric reentry",  making it likely that the NRI reports in Cracken's Threat Dossier should be regarded as incorrect, and the castle at Ta'a Chume'Dan is indeed the Fountain Palace.
- The Courtship of Princess Leia (First mentioned) (Indirect mention only)
- Young Jedi Knights: The Lost Ones (Mentioned only)
- Young Jedi Knights: Lightsabers
- The New Jedi Order: Agents of Chaos II: Jedi Eclipse
- The New Jedi Order: Dark Journey
- Dark Nest II: The Unseen Queen
- Legacy of the Force: Tempest
- Legacy of the Force: Sacrifice
- Legacy of the Force: Inferno
- Legacy of the Force: Fury