All of the following data dictionary tables have a LAST_ANALYZED column (replace * with USER/ALL/DBA as appropriate:
*_TABLES
*_TAB_PARTITIONS
*_TAB_SUBPARTITIONS *_INDEXES *_IND_PARTITIONS *_IND_SUBPARTITIONS(There's lots more in the histograms fields, but I'm not going that deep.)
Conversely, ALL_TAB_MODIFICATIONS shows rows inserted/updated/deleted (or the timestamp on which a table/partition/subpartition was truncated) since it had optimizer statistics gathered.