Oracle: How to convert to local time

alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
select
cast(from_tz(cast (to_date('2011-01-01 16:00:00') as timestamp),'GMT') at local as date) as LOCAL_EVENT_DATE
from dual;
alter session set succeeded.
LOCAL_EVENT_DATE
-------------------------
2011-01-02 02:00:00
1 rows selected