Oriental Fishbone Gallery

The organ museum is in the Trigram House (八卦楼 Bagualou) in northwestern Gulangyu; it is the only and the largest organ museum in the world. Matched with the piano museum in southeastern Shuzhuang Garden, it attracts a lot of music lovers from around the world. There are many styles of organ collected in this museum.

Admission is a steep ¥90 for adults, ¥50 for children/seniors, but you can just stand outside and take photos of the Jules Verne-esque octopus statue.

A museum focusing on the colonial-era foreign residents of Gulangyu, in a building that was once a villa belonging to the Singapore-based OCBC Bank.

A rather small museum dedicted to Zheng Chenggong, or Koxinga as he is generally known in the West, who made his mark in history by driving the Dutch out of Taiwan in the 1660s. His headquarters were on Dragon Head Hill at the south end of Gulangyu; a watchtower and some other fortifications remain, and the statue is nearby (see listing below).
Having defeated the foreign devils, Koxinga is one of the few people regarded as a hero by the current governments of both China and Taiwan. Things the museum's account (Chinese only) does not mention are that his father, a seafaring merchant from the Quanzhou area, dabbled in piracy and that his mother was Japanese.
As the Manchu conquerors who became the Qing dynasty moved south, the father surrendered and became a Qing official, but the son remained loyal to the Ming and fought on; at one point, his armies got as far as menacing Nanjing.
Eventually, he found himself defeated on the mainland so he went off, bringing most of his army, and took over Taiwan. Koxinga's arrival was the first major Chinese incursion into Taiwan; many of his troops stayed and settled. This was followed by a surge of other immigration, mainly from the Xiamen, Quanzhou and Zhangzhou areas. Modern Taiwanese is essentially the Minnan dialect of those cities.

This is the highest point on the island with great views as far as Xiamen. Entry included into Buddhist temple, the Aviary and a cable car ride to the aviary on Yingxiong Hill. Warning: climbing to the top involves a lot of stairs, so probably not good for young children or the elderly.