As architect I also was interested in architecture in Singapore. The city has an interesting mix of colonial- and modern architecture. Colonial Quarter is the place to be if you want to see Victorian architecture. Here you will find buildings like the City Hall, Supreme Court, Old Parliament House, Victoria Theatre and Raffles Hotel.
Other interesting architecture are the Chinese shophouses. You can see those shophouses at several places in Singapore. Some nice examples of shophouses with woodwork and carved panels can be seen in Mosque Street and Blair Road in Chinatown. But you also will see shophouses in Little India and Kampong Glam. Certainly in Little India there are some very colourful houses. Best example is the house at the corner of Belilios Lane. Other shophouses can be seen at Emerald Hill, which is near Orchard Road. The most famous shophouses are located along Singapore River at Boat Quay and Clarke Quay. This area also is very cozy to go for a drink or dinner.
But there also is modern architecture in Singapore. The Singapore skyline is wonderful with buildings like Marina Bay Sands, Singapore Flyer and all the skyscrapers near Marina Bay. And not to forget Esplanade and the Art Science Museum. To see those buildings, just walk around Marina Bay. A tip I can give for people who are interested in developments or architecture in Singapore is to visit Singapore City Gallery. This gallery has a huge model of the island and Singapore city. At weekdays there is a guided tour at 11.30am.