Recent activities are listed on the Overview for each project, as well as on the All Projects - Overview section for all projects. They list the most recent activity at the top as a record of anything that has happened with a project.
You can quickly filter the list by simply clicking on one of the major activities at the top of the page. Each one of them shows the number of activity associated with it and all items in the filter will be displayed in the list below the filters shown here:
Note that these stats refer to current statistics in the application, not the full history. For example, if you have a total of 3 tasks on a project and you marked them complete and then later marked them incomplete, it will show that you have 0 completed tasks (not 3 completed tasks even though they were marked completed in the past).
You can also quickly filter the list by date or by specific people using the grey bar on the top left of the Overview section as shown here: