During the reigns of Fath-Ali Shah and Naser al-Din Shah in Tehran, many buildings were constructed for religious, political, recreational, and other purposes—such as gardens, palaces, royal residences, schools, mosque-schools, and bazaar mosques. Because of the special place of education and learning in the beliefs of the Iranian people, as well as the emphasis of the Holy Qur’an on acquiring knowledge, education held great importance and was regarded as a social and doctrinal activity. The mosque-schools, which served both religious and educational functions, featured richly crafted decorations, including tilework, brickwork, stone carving, and wooden ornamentation containing geometric patterns and muqarnas. The aforementioned tilings exhibit visual richness that can be examined through Gestalt theory. The relevant principles include role and background relationships, similarity (similar dimensions), proximity (combination and proximity of edges), form and background, common destiny, symmetry, overlap, and continuity. This research aims to study the composition and decorations of tiles based on Gestalt theory, as well as to understand the inscriptions’ use, content, and meaning on the tiles of Qajar-era mosque-schools in Tehran. This descriptive and analytical study classifies the decorations and analyzes the inscriptions’ concepts to reveal their themes. Data collection was done through library and fieldwork, and the statistical population consisted of 9 Qajar mosque-schools in Tehran during the Qajar period, including Nizam-al-Dawlah, Moshir-al-Saltaneh, Haj Rajab Ali, Haj Qanbar Ali Khan, Moaz-al-Dawlah, Marvi, Khazen-al-Molk, Mahmoudieh, and Filsof-al-Dawlah, which contained tile decoration. During the Qajar period, tiles were widely used to decorate, repair, and renovate buildings. Unlike in previous periods, tiling during the Qajar era was not limited to mosques, tombs, and khanqahs; it was also used in palaces, mansions, city gates, and government institutions. The most common technique was the seven-color method, though underglaze painting also played an important role. Most buildings were constructed during the reigns of Fath Ali Shah and Nasser al-Din Shah and feature tiling art using seven-color techniques, pomegranate flower motifs, underpainting, portraits, seven-color moqarans, ghazi maghazi, knot-and-loop mosaics, and black ink mosaics. The tile motifs are floral, human, and geometric. Their use can symbolize nationalism and serve to achieve a specific goal. These decorations have a special place in the propagation of political discourse in Qajar-era buildings. In a way, they can be considered the product of the Qajar kings’ understanding of Khosrovani’s wisdom and utopian ideals. Similar to other artistic fields, such as painting, the Qajar government used myths and symbols, such as the royal crown, to consolidate and legitimize its rule when constructing mosques and schools. Gestalt theory relies on the relationships between parts and views the whole in the context of these principles. According to the principle of similarity, the human eye perceives visual elements that are similar in shape, color, size, dimensions, direction, and distance as distinct sets and patterns. In the tile decorations of these mosque-schools, there is overall harmony and coherence, despite the diversity in the designs and shapes of the tilework. These verandas surround the central courtyard and have unity in their overall form. The principle of form and ground is another principle of Gestalt, in which all elements can be divided into two parts. First, there is something that is clear and prominent and appears to be the main subject, and the other is its background. This principle is more important in inscriptions with calligraphic decorations like tiles with calligraphy on a blue background. Another Gestalt principle considered in the tile decorations of Qajar mosques and madrasas is the principle of symmetry. Despite the differences in the text inside the tiles, we see order. Many mosque tile designs are symmetrical, and despite slight differences, the principle of symmetry is highlighted. According to the principle of proximity, elements that are closest to each other are seen as a single whole or group. The proximity of visual elements is the simplest condition for seeing them together. It can be said that most of the principles of proximity gestalts (contact-integration-proximity of edges) have been used in the inscriptions. For example, the principle of proximity of edges is clear in the inscriptions of the Nizam al-Dawla mosque-school. The calligraphic writings that were placed within the frames of the inscriptions, in uppercase and lowercase letters, created a strong gestalt in the work. This principle is considered in the rest of the mosque-school inscriptions of the Qajar period. In order to examine the principles of proximity of edges, calligraphic letters with a third line are placed regularly next to each other. These letters are not separate from each other but rather appear as connected letters. In some parts, the letters are placed next to each other or even on top of each other, which is at the same time legible and orderly. In composition, the principle of grouping different elements together is achieved by using a structure and an external element. One of the most common methods of combining visual elements is to underline patterns and letters and enclose them within a frame. In the motif of tiling, smaller gestalt elements are overshadowed by larger ones, or larger ones cover smaller ones. Flower pot motifs on tiles are easier to understand than tiny flower and leaf motifs. At first glance, viewers see and understand the larger components. With further reflection, they see the smaller components. The motifs have interdependent designs that represent a single principle. The human eye tends to follow elements in a visual structure as long as the motifs remain unchanged. It tends to follow smooth elements much more consistently than elements with broken lines and angular patterns. According to the principle of continuity, the human eye tends to follow elements in a visual structure as long as the pattern’s progression remains unchanged. This principle forms the basis for understanding tile motifs and inscriptions in the gestalt of integrity. The components that form a Gestalt are seen as a single group. Regardless of how different or far apart the motifs and elements in a structure are, they all reach a common goal by following a similar process. Even in many of these motifs, there is no need for mere similarity or identical movement; what is important in this principle is a common goal and destiny. Despite the variety of motifs and the different framing and compositional arrangements in the layout of inscriptions and tilework, a shared perspective can be perceived across all of them, which is spiritual and religious in nature. That is, these spaces offer an environment that is both spiritual and educational, conveyed through symbolic and mythological elements rooted in Iranian culture and inscriptions. They are designed to engage the viewer’s understanding, providing a calm setting, away from the bustle of streets and markets, conducive to both intellectual and spiritual experience. The inscriptions used in Qajar-era mosque-schools can be divided into six categories according to the themes used within them: Quranic verses, prayers for the pure Imams, Shiite doctrinal principles, Shiite poems and praise of Ashura, and references to important moral principles that were worked on at the entrance of the buildings, on the outer walls of the building, in the courtyard, or above the porches and above the entrance doors of the interior spaces. A notable point in the inscriptions is the color used in the writing and the background of the inscriptions. This color choice has been made consciously to the extent that they are easily readable from a distance, or the color combinations used in the brick and tile decorations of the buildings make the designs clearer.