Pasto Viejo is a barrio located in Cayey, a municipality in the southern interior region of Puerto Rico, positioned in the foothills and elevated terrain characteristic of the island's central mountain zone. The barrio spans approximately 4.16 square kilometers and represents part of Cayey's rural and semi-rural landscape, where the topography transitions between agricultural land and residential development typical of inland communities away from coastal influences.

The name Pasto Viejo, referencing "old pasture," reflects the barrio's historical character as grazing and farming land. The terrain in this part of Cayey is characterized by moderate to steeper elevation, supporting a mix of agricultural uses, small family farms, and dispersed residential properties. Unlike the densely platted urban neighborhoods found in Puerto Rico's metropolitan areas, Pasto Viejo maintains a more rural development pattern with larger individual parcels, open land, and agricultural spaces interspersed with residential holdings.

Property in this barrio typically consists of larger acreage lots rather than the small urban subdivisions found in coastal municipalities. Owners and investors in Pasto Viejo often hold land used for farming, livestock, or residential purposes on properties that may range from several thousand to tens of thousands of square meters. The development pattern reflects the barrio's location away from major commercial corridors, making it attractive to those seeking rural property, agricultural land, or quieter residential settings within Cayey's municipal boundaries.

The property landscape in Pasto Viejo is documented in Puerto Rico's cadastral registry, and Propieda maintains access to parcel records and ownership information for properties throughout this barrio.

Cayey: Cayey, in the central mountains along highway PR-52, serves as a gateway between San Juan and Ponce. Home to a University of Puerto Rico campus, this municipality offers mountain living with reasonable access to both coasts. The area attracts academics, professionals, and those seeking cooler climate.