Dist of Columbia
I see that someone posted the Age 2 wonders, but I think you meant the white background special buildings.
Three Field Farm
Hope this helps!
Thanks Bradley, this is exactly what I was looking for. I had a list of all the Wonders and Heroes already (but appreciate the effort Mouldy!), so figured what I was missing special building which in fact I am: Castle is the winner (good guess Mouldy!).
I'll be sending off an email to Eric below to get this straightened. The BGG community comes through again, can't believe I was able to get this all cleared up so quickly!