In case you are a frequent traveler and like vacationing with your family or friends, you sure are supposed to know about the place you are about to travel. Here is a collection of articles which will help you find helpful information like modes of travel, best season to visit, etc about these places.

ImageMercer, the global financial and HR consulting firm, recently came up with a list of world's cleanest cities. Mercer took into account the air quality for the upkeep of streets and squares to produce the 2011 rankings.

Here are the ten cleanest cities in the world:

1. Calgary (Canada)

Calgary is positioned on 'the fringe of Canada's largest energy belt and enjoys lower taxes and less stringent regulations', says the Forbes study.

Calgary's economy is also dominated by oil and gas industry, apart from manufacturing and services.

Calgary, which boasts of impressive infrastructure, is well placed to be one of the fastest growing urban centres in the world.