Find out when your index was last rebuilt / reorganized

I've recently come across a database, which has very high fragmentation on large tables. Page count > 1'000'000 with fragmentation 99,... I would like to know how long this table has gone without a reorganize / rebuild. That way I can review changes made on that date, to try and find a cause. (Also it'd look nice on my report "this database has not been properly maintained since...) As I'm in the process of setting up a job to quickly reorganize the affected tables (this night probably), any solution that could offer me a history of index operations would be much appreciated. If not, simply knowing that I can check this data in the future would be very helpful.