Changi Airport's control tower and the Merlion topped a list of 53 buildings, sites and structures in a study on perceptions of Singapore's built heritage.

The airport's iconic tower came in first while the mythical creature slithered into second place in an Institute of Policy Studies' survey of 1,500 people aged 18 to 70, who ranked the duo as the "most important to them".

The Singapore Science Centre and the Botanic Gardens - a Unesco World Heritage Site - were also ranked highly.

When it came to other landmarks, the old and the young were split in their opinions.

For instance, Bukit Brown Cemetery loomed larger in the minds of the youngest group of respondents, aged 18 to 28. The researchers said this could be due to the ground-up social media movements advocating its conservation.

Meanwhile, the oldest cohort, aged 49 to 70, who perceived colonial buildings such as the former Supreme Court as important - as well as those who liked the appearance of infrastructure such as Changi Airport's control tower, the Benjamin Sheares Bridge, Clifford Pier and Tanjong Pagar Railway Station - were more likely to have a strong sense of national identity.

This link was not as apparent among younger respondents.

The two-year study, which is supported by the National Heritage Board's (NHB) heritage research grant, is the first of its kind. It sought to establish a framework as to how Singaporeans appraise the country's built heritage.

IPS senior research fellow Natalie Pang said the study primarily revealed the diversity in public perceptions of heritage.

The research work, which was centred on built landmarks that are at least 30 years old, also found that sites where public access is limited were ranked lower by respondents. These included Pearl Bank Apartments, the NUS Baba House, Kallang Airport and the Bukit Timah Railway Station.

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On the popularity of the Merlion and Changi Airport's control tower, Dr Pang noted that the two have, over time, become iconic symbols associated with the country.

For instance, the Merlion likely emerged on top because of its prominent role in branding Singapore as a tourist destination, its promotion of a unique Singaporean identity and its symbolism of a nation eager for economic success, she said.

Meanwhile, post-1965 structures such as Pearl Bank Apartments, Golden Mile Complex, People's Park Complex and the now demolished Rochor Centre, received much less love from respondents, who found them relatively unappealing compared with other sites.

For instance, even though respondents aged 29 to 70 ranked People's Park Complex highly in terms of their awareness, knowledge and memories of the structure having shopped there growing up, they did not consider it much more important or aesthetically appealing than younger respondents.

Dr Pang said this shows a disconnect between architects' visions and users' experiences.

She said: "This translates into the need to educate the public on modernist buildings, as well as to ensure that impact assessments include criteria that take into account the importance of evaluating post-independence buildings as markers of modern Singaporean architecture."

Dr Pang, noting that conversations on heritage often take place among academics, policymakers, heritage-related practitioners and activists, added that more effort should be made to consider the everyday meanings associated with sites in planning and heritage conservation decisions.

She said: "One of the key takeaways is that heritage sites contain diverse connotations across social groups. We should not be using a single, monolithic approach to evaluate all of Singapore's heritage sites."

The team believes the findings can help heritage bodies adjust promotional programmes and policies.

Responding to queries from The Straits Times on how NHB plans to use the study's results for heritage impact assessments and its heritage blueprint, which is in the works, its spokesman said the findings will help it to "understand the different factors that affect the public's appreciation and understanding of heritage".