It is a blazing Tuesday morning and beads of sweat are glistening on Mr Mak Chin On's forehead.
Boys in uniform a quarter of his age walk past him as he looks up at the imposing clock tower of his alma mater - Chinese High, now known as the Hwa Chong Institution (HCI).
"This used to be a hall where we would have our music lessons," saids the 73-year-old nursery owner, pointing at the open space beneath the tower before breaking spontaneously into song.
During my time, only the top eight classes got to study in the clock tower classrooms, so we really worked hard to get in.
MR LI JIE XUN, 33, who made it to one of the eight coveted classrooms.
When you've done something wrong, that's the place you go to get punished!
MR NG CHENG KOK, 76, who graduated in 1959, referring to the time when the principal's office was located in the clock tower.
HOME AWAY FROM HOME
Every time I head back to boarding school... the clock tower is the first thing I see. It's the thing that lets me know that I'm home.
MR LIM HAN XIN, 22, who stayed in the on-campus boarding school during his six years of study at HCI as a Malaysian scholar.
I remember when I left the school, I looked up at the tower and told it to wait for me to come back and repay it one day.
MR MAK CHIN ON, 73, who contributed plants and shrubs from his nursery to the area surrounding the tower.
The 36m-high clock tower has stood witness not only to the maturing of generations of boys, but also to Singapore's journey from colony to country.
Built in 1925 with generous donations from prominent Chinese leaders such as "Sugar King of Java" Oei Tiong Ham, the tower has been the backdrop for various episodes in Singapore's history.
The Japanese used it as a vantage point and surveillance tower during their occupation of Singapore from 1942 to 1945.
It also served as a temporary concentration camp for prisoners detained during the brutal Sook Ching massacre, thought to have taken the lives of at least 5,000 men.
The clock tower also bore witness to the tumult of the 1950s and 1960s, when many students from the school took part in protests against the colonial government, resulting in arrests and detentions.
The tower's four-faced clock, which was destroyed and removed during World War II, was restored only in the early 1970s, when the late Singaporean tycoon Tan Keong Choon - the nephew of the school's founder - had Japanese watchmaker Seiko donate a new timepiece.
The clock tower would go through another round of restoration and expansion in the 1990s, when a bigger clock, a new library and a larger entrance added to its grandeur.
The clock tower that has stood throughout the changes of a chaotic century was gazetted as a National Monument by the National Heritage Board in 1999.
Today, tales of the clock tower's former ruin and abuse remain alive in the playful ghost stories inspired by its rich history.
Mr Li Jiexun, a 33-year-old alumnus who now teaches chemistry at HCI's junior college section, said: "We've all had seniors scare us with ghost stories about the clock tower, like how people who go up never come back down."
But to 76-year-old Ng Cheng Kok, an old boy who graduated in 1959, the clock tower was scary not for horror stories but the principal's office. "When you've done something wrong, that's the place you go to get punished!" said Mr Ng, now a retired real estate developer.
The principal's office has since moved but the large, airy classrooms flanking the clock tower remain. These are reserved for the brightest students.
"During my time, only the top eight classes got to study in the clock tower classrooms, so we really worked hard to get in," said Mr Li, who managed to make it to one of the eight coveted classrooms.
The classrooms are now reserved for students in special programmes like the Science and Math Talent Programme.
Designed by Swan & Maclaren, also behind Raffles Hotel and Sultan Mosque, the clock tower was always meant to inspire excellence.
With neoclassical elements like stately columns, arched doorways and windows, the clock tower is said to evoke elite institutions such as Cambridge and Harvard.
It is fitting, then, that HCI should be one of the island's most prestigious institutions. As the first secondary and high school to be established specifically for the Chinese community in Singapore, the school was initially named the Singapore Nanyang Overseas Chinese Middle School.
To students, the clock tower was not just a representation of their school, but their home as well.
Mr Lim Han Xin stayed in the on-campus boarding school during his six years of study at HCI as a Malaysian scholar.
The 22-year-old Batu Pahat native, who is currently studying psychology at the University of California, Los Angeles, said: "Every time I head back to boarding school, no matter where I'm coming from, the clock tower is the first thing I see. It's the thing that lets me know that I'm home."
The clock tower is a place of great sentimental value for many Chinese High old boys.
Said Mr Mak: "I remember when I left the school, I looked up at the tower and told it to wait for me to come back and repay it one day."
So has he honoured his promise?
Gesturing towards the carefully manicured plants and shrubs surrounding the tower, he says: "Well, you see all these trees? All donated from my nursery!"