A good book to start with
Casles and manors of Latvia by Albert Zarans
Riga 2006
ISBN 9984-785-05-x
I had it sent to me to Australia from the biggest bookshop in Riga called"Janis Roze"
163 of them,with the names of the German Baltic barons who built and/or owned them..
Magnificient photos. in latvian and English..
very intersting book.