The city maintained its peace during the Ayodhya-related riots in 1993. Even when the country's former Prime Minister Rajiv Gandhi was assassinated in Sriperumbuthur, barely 50 kilometers from the city, there never was any tension in the city itself. The worst kind of crime you will ever be a victim of is petty theft. Hence, secure your valuables. Being overcautious in crowded places is better than being sorry later on.
Pickpockets are inevitable in highly crowded places.
In the recent past, there were gang related incidents in dark corners of the city. Although it is believed that the situation is under control now, please avoid dark streets. The main streets are perfectly safe, even during the late night hours. Rest assured, Kanchipuram is probably one of the least likely places in the world where you might become victim to a violent crime. Good conduct is mainly expected inside the temples.