Those who never knew that the Istana was built by 3,000 convict labourers will learn about this and other nuggets of information on Monday when guided tours of the Istana building are offered for the first time.

On the second day of Chinese New Year, volunteer guides from the Preservation of Monuments Board will give 45-minute tours offering visitors a glimpse into historical, architectural and aesthetic trivia surrounding the 144-year-old national monument.

The tours will be offered on all Istana Open House days starting from next Monday's session.

Tickets for the tour cost $2 for children between the ages of four and 12, $4 for Singapore citizens and permanent residents and $10 for foreigners. Proceeds from ticket sales will go to charity. Tours, which will done in groups of 20, will be conducted at half-an-hour intervals from 9.30am to 4.30pm.