Water supply is widely recognized as one of the greatest challenges to urban living today. Whether negotiating shortage or excess, securing and sustaining a reliable supply of water for human consumption, health and sanitation, processing and manufacturing of goods, and all other aspects of life is a complex undertaking in urban contexts. To complicate provision even further, sources and resources of water are diverse, change over time, and interact with and are influenced by complex biophysical and cultural processes. People have been living in cities for millennia and across very different environments: from the earliest urban centers of the Near Eastern arid lands to the market towns growing along waterways and wetlands of northern Europe to mention but two profoundly different cases. How did ancient cities obtain water? What was water needed for?

To inform these questions, we have curated a collection of articles that address how ancient urban societies have dealt with water, securing supply and negotiating changes over time across a wide spectrum of cultures, environments, and periods of time. Within the wide range of articles offered by WIREs Water to date, our selection currently presents case studies that illustrate different regional and cultural contexts for two main reasons. First, we want to illustrate the sheer diversity and complexity of past water–city interactions, with a focus on the creativity, dynamism, and flexibility expressed by historical water supply systems. Second, we aim to expose some of the links between opportunities and challenges shaping the water–city interplay over the long term. In our globalized world, urban living is characterized by increasing speed in the way we operate, relate to our surroundings, and satisfy our needs. Modern urban water supply is largely dependent on pipeline provisioning for fast and reliable delivery. While this collection does not explore the contribution of historical developments to issues concerning present and future urban water systems, we hope that the articles presented will inspire thinking beyond our times and reflecting on how past urban societies have secured water provision over the long term.

Featuring profoundly different historical developments, the case studies in this collection illustrate some general threads running across three main topics.

供水被广泛认为是当今城市生活面临的最大挑战之一。无论是协商短缺还是过度，确保和维持可靠的水供应以供人类消费，健康与卫生，商品的加工和制造以及生活的所有其他方面，在城市环境中都是一项复杂的工作。为了使供应更加复杂，水的来源和资源是多种多样的，随着时间的推移而变化，并与复杂的生物物理和文化过程相互作用并受其影响。人们已经在城市中生活了数千年，并经历了非常不同的环境：从近东干旱地区的最早城市中心到沿北欧水路和湿地生长的集镇，这里仅提及两个截然不同的案例。古代城市是如何获得水的？需要什么水？

为了解决这些问题，我们整理了一系列文章，探讨了古代城市社会如何在各种文化，环境和时期内处理水，确保供应和谈判随着时间的变化。在WIREs Water提供的广泛文章中迄今为止，我们的选择目前提供的案例研究可以说明不同的区域和文化背景，其主要原因有两个。首先，我们要说明过去水与城市之间相互作用的多样性和复杂性，重点是历史供水系统所表现出的创造力，活力和灵活性。其次，我们的目标是揭示长期影响水与城市相互作用的机遇与挑战之间的某些联系。在我们全球化的世界中，城市生活的特点是我们的运作方式，与周围环境的联系以及满足我们的需求的速度不断提高。现代城市供水很大程度上依赖于管道供应，以实现快速可靠的输送。

该系列案例研究具有深远的不同历史发展，阐明了贯穿三个主要主题的一些一般性话题。