How was the French part of Hanoi differently built?

[mereena]

• The French part of the Hanoi was built as a beautiful and clean city with wide avenues and a well-laid out sewer system.
• The latest ideas about architecture and modern engineering skills were employed to build a new and modern city.
• The refuse from the old city drained straight out into the river but what was installed to create a hygienic environment in the French city became the cause of plague.