Wikipedia has several lists of oldest buildings:

List of the oldest buildings in the world

Oldest buildings in Canada by province or territory

List of oldest buildings and structures in Toronto

List of oldest buildings and structures in Macau

Oldest buildings in the United Kingdom

Oldest buildings in Scotland

Oldest buildings in the United States

List of the oldest buildings in Connecticut

List of the oldest buildings in Delaware

List of the oldest buildings in Massachusetts

List of the oldest buildings in New Jersey

List of the oldest buildings in New York

List of the oldest buildings in Pennsylvania

List of the oldest buildings in Rhode Island

List of the oldest buildings in Virginia

See also

List of the oldest churches in the United States

List of the oldest churches in the world

List of the oldest mosques in the world

Oldest synagogues in the world

Oldest buildings