I assume you want to retrieve that kind of information programmatically. From the ProcessEngine you can retrieve the historyService and create a query for "ActivityInstances", e.g. like
processEngine.getHistoryService().createHistoricActivityInstanceQuery()
.processDefinitionId("myProcess").processInstanceId(pid).orderByHistoricActivityInstanceStartTime().list();
Make sure that the history level of the engine is set at least to level "activity". Otherwise you will just see currently active ActivityInstances, but no historic ones.