Water is becoming a support for landscape and urban projects in a densely urbanised area settled along the Tagus Estuary, dubbed the City of the Tagus Estuary (CTE). Analysing two recent projects along and towards the Tagus Estuary hydrographic network, this article highlights how the most evident limit (the water) can function as the strongest binder, natural link, and shared public space of the CTE. Located, respectively, on the north and south banks of the estuary, the analysed projects become a way to think about urban strategies and promotions that use water as a way to build (re-build or reformulate) the image of the Lisbon Metropolitan Area. Today, open spaces bound to waterlines support an appealing and winning urban regeneration formula. Our goal is to understand what kind of role water is called to play with regard to the CTE. We ask: is the water called to play merely the role of building a new image of the city as a ground for investors? Is water the way to build a green and habitable CTE? This article concludes that the analysed projects contribute (as expected) to the promotion of the surrounding areas and propose appropriate solutions while occasionally overcoming the current local urban planning.