noun
castle entrance fee; admission fee (for a castle)
Specifically the fee to enter a castle, typically a historic site or museum.
姫路城の入城料は大人1000円です。
The entrance fee for Himeji Castle is 1000 yen for adults.
入場料 is a general admission fee for any venue, while 入城料 is specifically for entering a castle.
Compound of 入城 (entering a castle) + 料 (fee).