Updated: Mar 16, 2021
The Walker Estate, a grand, old turn-of-the-20th-century mansion, appeared in several episodes of Hawaii Five-0 and even more episodes of Magnum, PI. Here are the ones I could find listed:
Hawaii Five-0 : "The Ransom" (Season 3) - the home of Nelson Blake, father of the kidnapped child
"Let Death Do Us Part" (Season 9) - the Newhall home
"Invitation to Murder" (Season 10) - the Barlow home
Magnum, PI : "Never Again . . . Never Again" (Season 1) - unknown
"Curse of the King Kamehameha Club" (Season 1) - the home of Sidney Dollinger
"Of Sound Mind" (Season 3) - MacLeish home, which Magnum "inherited"
"Holmes is Where the Heart Is" (Season 4) - unknown
The Walker Estate is protected as a property on the National Register of Historic Places.