Ako was a small but rich fief thanks to salt production on the coast. The castle was built in 1645 by Asano Naganao on the alluvial plain of the Chikusa River. It used to have 12 gates and 10 yagura towers and as it stood immediately at the seaside, one could set sail from docks located in the castle. Salt making took place in salt pans at the seaside and the salt from Ako was sold in the capital Edo and all over Japan.
Tourism in Ako has been built around the Forty-seven Ronin memories, but the problem is that there is not really much to be seen. The castle was dismantled in the early Meiji-period, and although a wall and one gate and one tower have been rebuilt, it doesn't add up to much, especially as - in contrast to for example nearby Tatsuno Castle - the castle grounds have only partly been restored. They just peter out in fields and a large parking lot and have not been made as a whole into a park. There is no unity.
[Restored yagura tower of Ako Castle]
The largest space inside the castle grounds is taken up by the Oishi Shrine dedicated to the leader of the Forty-Seven Ronin, but this was only built in 1900 and is a very commercial-looking affair, not more than a tourist trap. It is second-hand Shinto, and the Forty-seven Ronin statues outside are very ugly - there are more of these in the Treasure Hall if you can stomach the steep fee.
That leaves two things. One is the gate to the house of Oishi Yoshio (Kuranosuke), the Ako chamberlain who led the secret vendetta of the forty-seven. The gate is said to be the original one on which the messenger from Edo knocked, bringing the news of Lord Asano's forced seppuku.
[Gate to Oishi Yoshio's mansion]
The other structure of interested in the castle grounds - and for me the largest point of interest in all of Ako - is the Ako City Museum of History, built in traditional style at the site of the former rice storehouses of the castle. Its displays are mainly about salt production (tools, models) and the Forty-seven Ronin (ukiyoe). There is also a model of the type of ship that carried the salt, packed in straw, to Edo. Although there is nothing in English, two nice videos about both these subjects are shown as well.
[Ako City Museum of History]
Besides the castle and its attractions, Ako also boasts Kagakuji Temple, founded in 1645 as the family temple of the Asano clan - it features grave monuments (the main grave of Lord Asano is however in Sengakuji in Tokyo) and more Forty-seven Ronin replicas.
Don't forget to taste the local product - salt -, which is best done in the shape of the Shiomi Manju cakes sold in the town - as usual, the inside consists of azuki bean paste, but to the shell some Ako salt has been added.
Ako is easily accessible from the Kansai area. Its station, Banshu Ako, is on a branch line from the main Sanyo line, called Ako line, but there are through trains to Banshu Ako from Kyoto/Osaka/Kobe - otherwise, change trains in Himeji. The Ako castle grounds are 20 min on foot from the station. The Ako City History Museum is open from 9:00-17:00, but closed on Wednesdays and at year end/New Year. Entrance fee is 200 yen.