Unfortunately, the built-in calendar searches only in the close range, one year back and one year ahead.
With this app the searched period extends over 100 years into the past and 32 years into the future.
After the start and after the permission for the access all calendars are shown. By selecting a calendar you get to a sorted list of all past events of the last hundred years in this calendar. Reading in the events can take a few seconds if there are a lot of them.
Search in the past is preset and can be toggled to search in the future with the reload gesture.
When a search text is entered, all loaded events are searched, more precisely their date, description, location and notes. If a date is to be searched for, the search text must be entered in YYYY-MM-DD format. The app settings allow for case-sensitive searches. To speed up the search in calendars with a large number of events, the number of events considered can optionally be limited to 20,000.
All loaded events can be displayed and edited in detail.

Questions like

When was the last time I was at…?
When was I in …?
When did …?
How often …?
can be answered easily from now on.