Maardu is a town and a municipality in Harju County, Estonia. It is part of Tallinn metropolitan area, located about 15 kilometres east of the cap…Maardu is a town and a municipality in Harju County, Estonia. It is part of Tallinn metropolitan area, located about 15 kilometres east of the capital city. The town covers an area of 22.76 km² and has a population of 16,170.