This paper presents an application of internet of things to enable a smart city by monitoring crucial environmental parameters such as temperature, noise, pollution. The system is also designed to monitor and control street light and traffic signal for effective use of electrical energy and smooth vehicular transportation. All the necessary parameters to be monitored are sensed using various sensors readily available. The measured data from sensor is processed using intelligent microcontroller based system. This processed data is passed on to android smartphone through Bluetooth and made available wirelessly on the server for storage and access continuously through internet. This kind of monitoring system can be used to find out disturbances in different parts of the city and take appropriate actions accordingly.