1959年,美国的一位建筑师设计建造了一幢六层楼房和座落在楼顶上的空中花园。此后,许多国家相继修建了不少屋顶花园。近几年,我国南方一些大城市也进行了这方面的尝试。而在北方则无进行屋顶绿化的先例。北京市建成区内的绿化覆盖率平均只有 In 1959, an American architect designed and built a six-story building and an overhead garden on the roof. Since then, many countries have built a lot of roof garden. In recent years, some big cities in southern China have also conducted this attempt. In the north there is no precedent for roof greening. The built-up area in Beijing has an average of only the green coverage rate