How do Access the Archived Activities (Task/Events) and When the Activities get Archived?

Salesforce archives older activities tasks or events according to the conditions below:

•     Events with a due date greater than 365 days old
•     Closed tasks with a due date greater than 365 days old
•     Closed tasks without a due date that were created more than 365 days ago

Archived tasks or events activities can be viewed only in export files, printable view, or by clicking View All on the Activity History related list. You can also view an archived activity if you know the URL for the activity .

Administrators can delete archived activities using Mass Delete.

Archived tasks or events are not included in reports. However, you can report on open or completed tasks.