The Event Viewer is located under the Admin ->event viewer menu. It can also be added to site pages

This historical log includes database events such as event schedules, exceptions, account logins, module and page changes, user account activities, security role activities, etc. Authorized users can Send Exceptions to any email address.

The Host can add, edit and delete event records for all portals

Custom queries

Note: Ideally direct database queries should never be ran (instead the API should be used), however on occasion a site admin may need to run a direct database query to access eventlog records (e.g if the site is down). In this case a query such as that below should help identify the issue(s), and (optionally) filter them down. In this example the logproperties field is also cast into an XML datafield.

SELECT     

      LogServerName, 

      LogCreateDate, 

      CAST(LogProperties AS xml) AS Log, 

      LogTypeKey

FROM         

      EventLog

WHERE 

      LogTypeKey = 'GENERAL_EXCEPTION' AND

      DATEDIFF(mi,LogCreateDate, GetDate()) < 30

ORDER BY logcreatedate desc

Additional references

Analyzing an exploding eventlog