Trakai
Trakų Salos pilis
Trakai Island Castle
Free on the last Sunday of the month
The only Gothic island castle in Eastern Europe; houses the main museum exposition on the town, castles and Trakai region, plus 16 applied-art halls.
Karaimų g. 43C, Trakai,
trakaimuziejus.lt/en/apie-mus/salos_pilis/