Across the world, whether in wealthier countries or the others, it is not so difficult to find wide ranges of opportunities that have beed ignored. It could happen in terms of many fields, that sometimes seems covering  the majority of crucial aspects. Usually, these ignorance are the result of so many fault decisions that have been made during decades or even centuries. So, if there are solutions to solve them, for sure these solutions are related to many decisions as well. It means that everyone in this vast world, must find and figure out his role to go one step forward in order to help the world community overcome the related issues. The target of theses lines is to express some aspects that could help us think more about the subjects related to economy in its basic meaning, but more than that, in some aspects that are more related to environments, cities and buildings. Of course it seems almost impossible to find the most important ignored issue related to the mentioned fields, however, I try to express just one subject, and give my general ideas and feedbacks of the similar discussions during the 15-hour “Economics of Sustainability” course, lectured by Gonzalo Delacamara in IAAC’s 2014-15 Master of Advanced Architecture program. As it seems not so strange, there are a handful of countries that you could find a bigger gap between their opportunities and what they have decided during their history. Iran, as one richest countries of the world in terms of history and culture, is an impressive example to be think about its opportunities. In the past, more than today, Iranian people were be integrated to their culture, history, nature and environment in almost any aspect of their lives. It means that, any subject of these field, could be as effective and the more important ones. The same was about natural opportunities – or better to say – facilities and resources as well. One of these natural opportunities that had a significant importance on shaping the cities, and people’s lifestyles, was “Qanat”. So, throughout these lines, I tried to find out some guild lines and hints in order to figure out how Qanats could be as affective as they were in the past on shaping the cities and people’s lifestyles, in these decades that are unfortunately have been ignored by the people who make decisions about future of the cities in Iran. When you go back to 3000 BC, you can find a system of irrigation in Persian lands of the great Iran  called “Qanat”. References to qanat systems, known by various names, are fairly common in the literature of ancient and medieval times. The Greek historian Polybius in the second century B.C. described a qanat that had been built in an Iranian desert “during the Persian ascendancy.” It had been constructed underground, he remarked, “at infinite toil and expense … through a large tract of country” and brought water to the desert from sources that were mysterious to “the people who use the water now.” Qanats are underground tunnels, with a canal in the floor of the tunnel, which carries water.  At regular intervals, well-like openings extend from the surface to the tunnel floor, and it is through these openings that the tunnels were built and through which they are maintained. The underground nature of the canal reduces evaporation in the hot and windy desert, and amazingly allows 22,000 qanats to operate in Iran even today. Qanats originate in highlands, with a mother shaft as deep as 400 meters, and the tunnel floor slopes at a moderate angle toward its destination, which can be up to 160 kilometers away. The difference between the qanat and a surface canal is that the qanat can get water from an underground aquifer, so a surface river or stream is not needed. Since it travels at a slope independent of the surface features, it can go in a straight line. The water carrying canal in qanats were usually lined with stone or tile to reduce water loss. Qanats have been found throughout the regions that came within the cultural sphere of ancient Persia: in Pakistan, in Chinese oasis settlements of Turkistan, in southern areas of the U.S.S.R., in Iraq, Syria, Arabia and Yemen. During the periods of Roman and then Arabian domination the system spread westward to North Africa, Spain and Sicily. In the Sahara region a number of oasis settlements are irrigated by the qanat method, and some of the peoples still call the underground conduits “Persian works.” In the Middle East several particularly interesting qanats constructed by Arab rulers of early medieval times have been excavated. In A.D. 728 the caliph of Damascus built a small qanat to supply water for a palace in the country. A century later the caliph Mutawakkil in Iraq likewise constructed a qanat system, presumably with the aid of Persian engineers, that brought water to his residence at Samarra from the upper Tigris River 300 miles away. Qanats were an important factor in determining where people lived. The largest towns were still located at low elevations on the floors of intermontane basins and in broad river valleys. Most of these early settlements were defended by a fortress and watered by hand-dug wells sunk into a shallow water table. Qanats enabled these settlements to grow by tapping water-rich aquifers located deep beneath neighboring alluvial fans. Even more dramatically, qanats made possible the establishment of permanent settlements on the alluvial fans themselves. Earlier settlers had bypassed the areas because water tables there were too deep for hand-dug wells, and the wadis on these slopes were too deeply incised in the fans for simple diversion channels. In these locations,qanats tapped adjacent aquifers with underground tunnels fed with water drawn from upslope alluvial deposits in mountain valleys. For the first time, at these higher elevations, small qanat-watered hamlets appeared. According to the previous lines, there is no way do deny the crucial importance of the qanats’s role on the daily lives of Iranian people, and shaping the cities’s main boundaries and divisions. Besides, there are some other lands that are using this  – let’s say technology – nowadays. Just to have an overal glance over some examples, the qanat system in Turpan, China, is still very much in use. In the Sahara region a number of oasis settlements are irrigated by qanats, and some still call the underground conduits “Persian works. The Palestinians and their neighbors had for some 2000 years irrigated terraces of olive groves, vineyards, and orchards with water tapped from some 250 qanat-like tunnels beneath the hills on the eastern shores of the Mediterranean. But today the terraces and tunnels are largely abandoned-unused since the day in 1948 when Palestinians vacated following the creation of the state of Israel. The demise of these irrigation systems is, according to Zvi Ron, an Israeli geographer has mapped the tunnels, a human, ecological and cultural tragedy. Qanats are to this day the major source of irrigation water for the fields and towering hillside terraces that occupy parts of Oman and Yemen. They have for some 2000 years allowed the villages of the desert fringes of the Arabian Peninsula to grow their own wheat as well as alfalfa to feed their livestock. In these villages, there are complex ownerships of water rights and distribution canals. In Oman, their importance was underlined in the 1980s with a government-funded repair and upgrade program. Furthermore, there are still many examples of qanats in some Iranian cities and rural areas, and the methods used in Iran today are not greatly different from the system devised thousands of years ago, and I shall describe the system as it can now be observed. The project begins with a careful survey of the terrain by an expert engaged by the prospective builders. A qanat system is usually dug in the slope of a mountain or hillside where material washed down the slope has been deposited in alluvial fans. The surveyor examines these fans closely, generally during the fall, looking for traces of seepage to the surface or slight variations in the vegetation that may suggest the presence of water sources buried in the hillside. On locating a promising spot, lie arranges for the digging of a trial well. According to the official statistics of the Islamic Republic of Iran, there are more than 164.000 qanats existing throughout the current Iran’s boundaries, that are mostly located beside the dessert urban and rural areas. But now, It might be interesting to figure out how could we develop urban infrastructures, using qanats. Tehran, as the political and economic capital of Iran, has an amazing network of qanats under its ground. During the history of the city, in some periods, we witnessed more attention to this potential, paid by the governmental organizations. For instance, Qajar royal family, were much into qanats and finding ways to use them in a more efficient way. So as far as the statistics, there are about 500 qanats that exist in Tehran right now, but the point is only 150 of these qanats are being used for some goals, however, each qanat, may be perform as a super vital facility in order to develop a city, for instance in Europe. Furthermore, during some researches done by Reza Daneshmir & Catherine Spiridonoff, the two famous Iranian architects, there is another missing point in the field of qanats in Tehran, that is the fact that most of the qanats in Tehran are under the freeways and expressways. The point is that we have a couple of main infrastructures in metropolises like Tehran, but these are not useful for us, unless we could find a solution to use them in an cooperative way. As soon as we find an proper solution, we could say that we, fortunately, have many opportunities to have a city as an impressive sample for the next cities. And from my point of view, it seems that the most important infrastructure that has been ignored by the people and governmental organizations is qanat network. There are a couple of long-term plans for Tehran to be much greener than today, and I think, there is no need to install many new green facilities. What comes to my mind is to use the current huge opportunity – qanat network – as the main supporting infrastructure in order to push the green facilities of the city in the proper position, so that they could be as generative as possible. If it happens, we would have a kind of intelligent network, that defines the boundaries of green parts of Tehran automatically. Believe it or not, whole the cities of the world, must put themselves in a self-sufficient manner, in an early future. Maybe nowadays some city councils are satisfied with themselves that they can follow the first self-sufficient cities, and use their experiences, instead of costing their own money, time and energy, but, there is no way to be sustainable, if a city looks forward to survive. Clearly, the best solution for each city’s decision-makers is for the first step, use their local opportunities. As well, it will not happen unless beside making wise decisions, people in each level of societies, define their exact role to develop their sustainable potentials and push them into the economics wheels. Otherwise, I highly believe that we can not count on the other’s solutions, since all the large scale issues are much integrated to each other.