Global 'Last updated' timestamp
If by "Last Updated" you are only talking about nodes, then yes, you can.

Create a new view for content (using views module), add a block display, do not filter by any content type, but I think that you can keep the "Published" status. Sort by updated time, descendant, set the pager to show only 1 node. And set the display to only show the updated time. That's all.