Joshua built the Old House for Naomi in 1767 which is the first time I recall this fact.
alwaydavid is correct in that this is the first and only time on the show that the background of the Old House is mentioned. In this ep Stokes tells Nicholas that Joshua built the Old House as a gift to his bride Naomi. (I've always taken that to mean it was a wedding gift. But who knows? Though the year would seem appropriate for that sort of circumstance.) When Naomi hands over the deed to Barnabas in Ep #395, she says the deed is in her name and she's giving it to Barnabas as a wedding present (so Joshua won't have the last word, which would be quite ironic if Joshua did indeed build the house for Naomi as a wedding present). She further explains that the house is hers to do with as she chooses.
The interesting thing about all that is, considering the Collins family had been in Collinsport since the 1600s, where did they live before the Old House was built?
I also love how during his first infamous visit to the Old House in Ep #475, Stokes describes the house as very early Greek Revival before they learned the true art of it. (Dishing out nothing but compliments in that scene.
) And I should say so because the Greek Revival period in American architecture is considered to be 1830-1850.