The Civic District is full of well-known national monuments, but few know about the trees that have stood quietly alongside them for decades.

To shed more light on them, the National Parks Board (NParks) said on Sunday that it will launch a 3km-long Civic District Tree Trail on May 1. This will include monthly guided walks and markers at all 20 stops along the route, which starts at the entrance of the Istana and ends at the Raffles' Landing Site.

Some of these trees have been around for key milestones in Singapore's history. Some of the heritage rain trees in Connaught Drive, for instance, date back to the mid-1880s and bore witness to the first National Day Parade at the Padang in 1966.

Others are aesthetically appealing. The towering 25m-tall angsana tree around which the School of the Arts building was carefully built has a dense, dome-shaped, widespread and droopy crown.

Other trees are tied to the personal memories of Singaporeans. For instance, rooted within the Esplanade Park are five angsana trees that NParks and the Urban Redevelopment Authority transplanted late last year to re-create an iconic area familiar to dating couples between the 1960s and 1980s. The original trees, known as gor zhang chiu kar, meaning "under the shade of five trees", were removed after they were affected by fungus.

The trail will also draw participants' eyes to NParks' landscaping efforts rolled out to complement existing structures such as the 68m-tall Civilian War Memorial, which is flanked by the narrow conical crowns of the meninjau trees.

This could help to raise awareness of the significance of the natural heritage and how it complements Singapore's built heritage.

The trail could also drum up awareness of the benefits of Singapore's islandwide greening movement. Tree cover provides much-needed respite in a tropical climate like ours.

The trail will ideally prompt pedestrians to look up at the towering sentinels in our midst and appreciate the multiple roles they have played over the years.