The map above shows Albany County as it was in 1866. Notice that the four western-most towns, the Helderberg Hilltowns,  make up almost half the county. The highest point in the county is  West Mountain in Berne.
The Helderberg Hilltowns comprise more than 40% of Albany County, yet they account for less than 4% of the population.  They're situated atop the Helderberg Escarpment which rises steeply from the Hudson River Valley below.  Situated as it is on rock, the area was challenging for the early farmers, and the Hilltowns  never really prospered. Today the towns of Berne, Knox, Rensselaerville, and Westerlo are small communities where people enjoy a rural lifestyle amidst beautiful countryside.
Learn more about the Helderberg Hilltowns at their official town websites:

Town of Berne 
Town of Knox 
Town of Rensselaerville 
Town of Westerlo
These websites contain a wealth of information about the Helderberg Hilltowns:

Albany Hilltowns 
Helderberg Hilltowns Association 
Berne History Project
Dutch Barns, built in New York and New Jersey in the 18th and 19th centuries, are some of the last remnants of our pre-industrial agricultural way of life. There are several historic Dutch Barns still standing in the Hilltowns. Learn more at:

Dutch Barn Preservation Society 
Shultes-Malcolm Dutch Barn in Knox, NY