For historical reasons, Taiwan is one of the few places in the world where the density of bomb shelters is very high.

Take Keelung, a port city on the northeast coast of Taiwan, for instance. There were more than 600 air raid shelters in the city where a little more than 360,000 residents live. Some people describe that in Keelung, if you walk three blocks, you'll see a small bomb shelter, and if you walk five blocks, you'll see a large bomb shelter.

The main reason why such a great number of air raid shelters were built in Keelung is because of the importance of its location.

Just like the Philippines, Taiwan is part of the first island chain and has a similar colonial history. The Philippines had been ruled by the Spanish, American and Japanese. As for Taiwan, it was ruled by the Japanese in 1895 and had been colonized by the Dutch and the Spanish.

Being a port city located on the north tip of Taiwan, there were a lot of tunnels and bunkers being built in the 19th century during the Qing dynasty. For example, in 1884, Keelung had been occupied by the French for almost a year until the French was driven out by the imperial envoy, and the fortifications were strengthened after that.

During the Pacific War, Keelung became a main bombing target by the United States, hence most of the air raid shelters were built at the time.

For many Keelungers, their childhood memories involve carrying a lantern and going exploring bomb shelters in the neighborhood on Lantern Festivals. There are even popular eateries and shops located inside air raid shelters where people can enjoy the natural breeze while they are eating beef noodle soup or doing manicures.

To make better use of these wartime sanctuaries, the Keelung City Government and local communities have come up with new ideas to transform bomb shelters into trendy restaurants, cultural and creative spaces, even an observation tower with elevator and art corridor.

Of course, Keelung is not the only city in Taiwan which has a high density of air raid shelters. Kinmen Islands, a group of islands governed by Taiwan but located closer to Mainland China, is another instance of how dense bomb shelters can be built.

In the main island of Kinmen which is only 150.46 square kilometers, there are more than 1,000 air raid shelters located. Not to mention basements, underground tunnels and ammunition dumps which were built for soldiers and civilians to hide and store live ammunition and explosives.

Nowadays, Kinmen has transformed into a popular tourist spot and some of the most popular gifts and souvenirs people buy in Kinmen such as Kaoliang liquor and kitchen knives made from cannonballs are related to its history of being a battlefield in the past.

The cellars used to store Kaoliang liquor by the Kinmen Kaoliang Liquor Inc. were actually tunnels used to store hydrogen tanks and oil for civilian use, and a power plant established underground to avoid artillery attack.

While the number of bomb shelters and tunnels in the Philippines may not be as many as in Taiwan, the Malinta Tunnel was the one spot which left the deepest impression on me when I visited the Corregidor Island.

The experience of Taiwan transforming air raid shelters, tunnels and even military dependents' villages into tourist spots, like the Rainbow Village in Taichung, can serve as a reference for the Philippines to see if there are other ways the Department of Tourism or local governments can do to attract more tourists to visit these spaces that people paid little attention to.