Darnay Kálmán's abounding part of his certificate and manuscript collection came to Keszthely after World War II.
The collection consists of 80 000 items (250 000 pages), from which the earliest ones are from XVI-XVII. centuries. In the continuously growing collection there are documents connected to Keszthely, family and famous people's heritage, written documents and small prints about institutions, associations, and Lake Balaton's history.
There is a seperate poster collection covering topics from politics to health care, tourism and theatre offering wide range of materials to exhibit from the XIXth century till today.