Yelverton Manor was created to aid the conjunction of Lusst'ghaa and our world. According to the notes of Milton Yelverton, the building would have to mirror a building from the Land of Eternal Ecstasy.
Lust For Darkness (Spoilers)
The Manor is where Willard Yelverton gathers the Cult of Ecstasy for a grand ritual to open the doors to Lusst'ghaa. Several cultists die in the Land of Etneral Ecstasy and this causes others to doubt Willard and attempt to flee the cult. Willard kills some of them (Sabinian at least survives). At the end of the game, Amanda and Jonathan Moon set fire to Yelverton Manor.
Lust From Beyond: Prologue (Spoilers)
A newspaper clipping about the destruction of the Manor says it was destroyed on the morning of June 22, 2018. 13 people were dead were found, and 7 were injured.