The archiepiscopal castle which today houses the Boppard town museum was built in the 14th century by Prince Elector Balduin of Luxembourg and is located to the west of a keep built around 1265. The extensive museum collection covers the Stone Age and Bronze Age, through the Roman period, to the Middle Ages, and right up to the present-day.

A comprehensive collection of religious art draws attention to the religious life of the town and the history of the various cloisters, churches and chapels in Boppard. The collection also looks at the life of the Japan explorer Philipp Franz Freiherr von Siebold, who explored the as yet unknown islands of Japan in the 19th century under commission by the Dutch crown. The heart of the museum is dedicated to a collection of bentwood furniture by Michael Thonet. The carpenter and furniture manufacturer was born 1796 in Boppard where he established his carpentry business in 1819. Thonet ultimately became world famous after he went to Vienna in 1841 with his Viennese Kaffeehaus chair, which still enjoys great popularity today.