thanks a lot

depends on which country you write to- as far as American English is concerned, Bluemchen's suggestions is correct (as far as I know)

In the UK something like "Berlin, 25 July 2005" or "Berlin, 25/7/2005" would be more common.

Always a source of confusion that the Americans put the month first.

If you want to be certain of avoiding misunderstandings, write the month- it's not a problem with the date given by you (as there are only 12 months in the year, so it is clear that 07-23-2005 must refer to July), however, if you have the 10th of April, it can be unclear what is meant if you write 04-10-2005 or 10/04/2005, as it might be misinterpreted by members of the other culture as meaning the 4th of October