Castles of Slovenia - gradovi.net
The website was launched in 2004 and is frequently updated with useful information for researchers. For example, a special section is dedicated to stonecutter's marks and documents 75 of them. The web list of stonecutter's marks in Slovenia and abroad can be accessed here. The site also contains a dictionary of castelological terms.
The founder of the site is an enthusiast with a passion for mediaeval history, who even manufactures mediaeval armour and makes presentations and workshops about mediaeval combat and martial arts.