**1. Introduction**

The sustainable development of cities is one of the key challenges of the modern world. There are authors who believe that smart cities are just an example of another concept of the ideal city [1,2]. It should be also noted that, in theliterature, the concepts of sustainable city and smart city are sometimesinvestigated separately. Thomas L. Saaty and Pierfrancesco De Paola treat the sustainable city, smart city and compact city as separate models. According to the authors—taking into account the process of urban sprawl, the transformation of buildings and economic impact on the environment—the choice of a compact city model is the best solution for future urban design and planning [3]. Alessio Russo and Giuseppe T. Cirella point out that the features of a modern compact city support sustainable development [4]. In turn, Matthew E. Kahn claims that the improvements of information technology, and advances in the know-how on the reduction of pollution, and following it health benefits for residents imply that more cities will be striving for "smart" sustainable development [5]. Such a viewpoint is presented in the present paper.

A sustainable smart cityis aninterdisciplinary concept, and as such, it hasmany definitions, emphasizing various aspects and proposing different assessment indicators [6]. An attempt to systematize the concepts existing in that area was made by Mattias Höjer and Josefin Wangela [7], and [8], as well as Rasha F. Elgazzar and Rania F. El-Gazzar [9]. The latter of the aforementioned authors has been extensively discussing and clarifying the meaning of the words/concepts such as "smart", "sustainability", "sustainable development", and also the meaning of complex concepts such as "sustainable cities", "smart cities" and "smart sustainable cities". They also quote the definition of smart sustainable cities developed by the focus group on smart

sustainable cities adopted in October 2015 by the International Telecommunication Union (ITU—T Study Group 5), which reads as follows: "A smart sustainable city is an innovative city that uses information and communication technologies (ICTs) and other means to improve the quality of life, efficiency of urban processes and services, as well as competitiveness ensuring at the same time that that it meets the needs of present and future generations with respect to economic, social, environmental as well as cultural aspects" [10].

The above definition represents a holistic character of the reflections on sustainable smart cities. In the discussion on such a concept of urban development, the following notions are taken into account: "sustainability, quality of life, urban aspects, and the main topics comprise: society, economy, environment, and governance" [6]. As it was mentioned above, the knowledge about sustainable smart cities was created by the representatives of various scientific disciplines, who often worked in interdisciplinary teams and describe the problem from various perspectives, such as: social [11,12], economic [13], information technology (IT) and telecommunications [14–16], environmental [17], health [18–21], legal [22], transport and mobility [23,24], urban and spatial planning [25,26], etc. It should be emphasized that the recurring feature of the publications is that they do not concentrate on the discussion of one problem, but they show it in a broader context (therefore, the above pairing of the authors with a given aspect only informs that a given topic occurs in a given publication). The market offer involving the segmentation of the smart city is dedicated to an even wider group of recipients, including:


In the vast and diverse group of stakeholders, the architectural aspect, and the role of an architect in the development of sustainable smart cities, are getting lost. For example, in the above-mentioned, very comprehensive report [6] (pp. 6–7), the Table presents the definitions of "sustainable smart cities", assigning keywords to each of them. Further, there is no keyword of "architecture" among them. A very indirect reference can be seen in the definitions quoted below:


Furthermore, in the document of the Economic Commission for Europe Committee on Housing and Land Management [30] (pp. 7–9), from among the mentioned 72 smart sustainable city indicators, only the following ones have indirect reference to architecture:


The problem of overlooking architectural issues when considering sustainable cities was noted by Emile Mardacana who pointed out that, "The definition of a smart city based on six key smart elements, including economy, management, people, science and technology, life and the environment, ignores such a basic component as the built environment, which is a physical platform of a smart city" [31]. To provide an example, we can refer to publication [32], in which each of the six pillars (building blocks of a smart city) was assigned from 10 to 22 features. In the presented set there was only one, very general reference to architecture, in the context of the latest research conducted by universities "for cultural heritage, architecture, planning, development, and the like" [32], (p. 13). Therefore, it should be noted that: "Architecture is all around us. From our homes to our offices, our stations to our skylines, the built environment defines the world we live in [33]". It should be added here that even the concept of "smart city architecture" has been taken over by computer science and it does not apply to the built environment, but to the structure of software [34]. In turn, in the literature on the subject of architecture and urban planning, even if there are problems at the intersection of architecture and sustainable development and smart city technology, the authors focus on environmental or technological aspects, and the reference to architectural aspects is missing. Architecture appears only in general keywords such as "smart buildings" and "urban infrastructure", but with no specific information, for example, how the idea of sustainable smart city translates into the form or facades of buildings. Furthermore, yet the environment of sustainable smart cities is designed by architects in terms of usability, but also in terms of form. Architects provide a physical form for the entire ecosystem of solutions created by smart and sustainable residential houses, smart and sustainable public utility buildings, which in turn create smart and sustainable housing districts [35]. In this way, the external image (appearance) of architecture is created, which in turn translates into the image of districts and cities together with their recreation and rest spaces furnished with small architecture. On this point, it should be noted that the literature on the subject includes a few publications referring to a more general level, i.e., to the urban form of smart cities [36]. Yet, the image at the architecture level, i.e. the form of buildings, facades, roofs, details and what is happening in the space around these buildings—in terms of the development of sustainable smart cities has not been a popular research topic so far.

This particular aspect - the external image of sustainable smart cities and the role of the architects in their creation—is discussed in the article. It is the main objective. Furthermore, the indirect objective of the article involves the synthesis of knowledge and an attempt to define the elements of sustainable smart cities, whereof a designing process is within the competence of the architect. Due to the extensive subject matter, the article provides a limited scope of analyses, attempting to define the elements that shape the image of a sustainable, senior friendly city, and to identify the role of an architect in this context. We must add that in line with the accepted assumption, an elderly-friendly city should be understood as one that meets the following criteria set by WHO:


The world and Polish resources of scientific publications contain works that combine the issues of smart cities and senior-related issues in the following aspects:


At that stage of research, when searching through the resources of scientific publications published in the open access, as journals, books or conference proceedings, no scientific publication could be found that would combine the following aspects:


It seems that this may be a new approach to research problems.

It should be clearly emphasized that due to the presumed novelty of the undertaken topic, the research is in the initial phase, referred to as the indicative level. It consists in observation and general review on the investigated topic, during which we can identify some dependencies, but without diagnosing their origin. The rise to higher levels, i.e.;


requires in-depth research using scientific methods, techniques and research tools.

Thus, the paper:


As to the scope of the work, it should be added that due to the scope of the undertaken topic and that of the article, we had to omit some relevant and interesting issues, such as:


These issues will be the subject of further research and publications.
