When building a new synagogue or choosing one to join, there are lots of things we consider. Is the space conducive to prayer? Can I get a seat that I will be happy with? Is the community inviting? One aspect that we often neglect to take into account is whether the synagogue is built according to halachic guidelines. When relating to the laws regarding the proper place, time and manner for prayer, the Talmud tells us: "A person should always pray in a house where there are windows" (B. Berachot 31a, 34b). The Talmud offers Daniel's manner of prayer as a source for this requirement: "...he had windows open in his upper story, towards Jerusalem, and he kneeled upon his knees three times a day and prayed and gave thanks to his God as he did previously" (Daniel 6:11). What is the purpose of these windows? Commentators offer different insights. The reason for the windows may bear on the appropriate location for the windows in the synagogue, as we shall see. One commentator suggests that windows can assist concentration, as the supplicant looks heavenward during prayer (Rashi, 11th century, France). According to this approach the windows should be placed such that those praying can look at them during the service. Moreover, the windows should not open up to an area that will disrupt meditation. Perhaps the windows should even be high up, so that supplicants' eyes will be raised heavenward during prayer. Another commentator also suggests that the windows are aimed at improving application during prayer, albeit by a different means: Windows allow light to filter in to the synagogue and this has a calming effect on those present, allowing them to concentrate on their prayers (Rabbeinu Yona Gerondi, 13th century, Spain). Windows, according to this approach, should be placed so that they will allow light to pour into the space dedicated to prayer. A third approach draws from the biblical source where Daniel opened windows toward Jerusalem. Hence the windows must be situated facing Jerusalem. These openings are thus an expansion of the mandated direction of prayer, a way of further channeling our prayers through the Holy City (Maimonides, 12th century, Cairo). Elsewhere in the Talmud we are instructed to pray with our eyes lowered toward the ground and our heart raised heavenward (B. Yevamot 105b). If the purpose of the windows is to look yonder toward Jerusalem, commentators question how we can look out of the windows if we are enjoined to look down? One halachist suggests that the rule requires lowered eyes during prayer. If we lose concentration, however, we are advised to fleetingly look through the windows heavenward and in the direction of Jerusalem in order to refocus our meditation (Rabbi Avraham Abele Gombiner, 17th century, Poland). Others suggest that windows should be looked at before the onset of prayer, after which our eyes should be directed downward (Pri Megadim, 18th century, Lvov-Frankfurt). Thus the windows serve as a stimulus to bring us back to the task of heartfelt, sincere prayer. In a bygone era, windows were not nearly as common as they are today. Building technology did not allow for gaping holes in walls and the cost of glass was prohibitive. It is against this background that we can understand the question posed to Maimonides by a troubled observer who noted that there were many houses of prayer that had no windows at all. Why did the widespread practice entirely ignore the talmudic rule? In his responsum, Maimonides introduced a heretofore unheard-of distinction: Windows are only necessary for those who pray at home; synagogues, however, do not carry this requirement. Buttressing this distinction, Maimonides recalls that Daniel went home to pray and there he went to the window facing Jerusalem. Later halachists note, however, that the accepted practice is to have windows in the synagogue and not to reserve them for prayers at home (Pri Megadim). A further issue discussed involves whether the windows should be open or closed. Some authorities advocate closed windows, recommending that supplicants distance themselves from open windows (Rabbi Akiva Eiger, 18th-19th centuries, Eisenstadt-Posen). Other authorities advocate open windows. One halachist singles out the holiest day of the year - Yom Kippur - as the only time when windows need to be open during prayer (Pri Megadim). Indeed, we have testimony that the hassidic master Rabbi Haim Elazar Shapiro of Munkatch (1872-1937) would enter the synagogue on Yom Kippur eve and order those present to open all the windows. Esoteric tradition goes further, describing the number of windows needed. The Zohar dictates that a synagogue should have no fewer than 12 windows, corresponding to the 12 heavenly channels for prayer, one for each of the 12 tribes of Israel. This may be the source of the popular practice of having the tribes' insignia cast in the windows of the synagogue. One hassidic master who was steeped in the kabbalistic tradition, Rabbi Yitzhak Isaac Yehuda Yehiel Safrin of Komarno (1806-1874), even gave the minimum dimensions of each window: four handbreadths by four handbreadths. This indeed can be a tall order, and later authorities suggest that each window pane - rather than each hole in the wall - can be counted as a separate window (Rabbi Avraham David Warman, 19th century, Buczacz). Normative Jewish law adopts the position that the windows should face Jerusalem and advocates the kabbalistic 12 windows (Shulhan Aruch OH 90:4), though not all of them need to face the Holy City (Mishna Berura, ad loc). While the kabbalistic significance of these windows may be beyond the ken of many, we can nevertheless find relevance in the window requirement. Returning to Maimonides's responsum to the troubled observer: He concludes his answer by recalling that no wall or beam can separate between us and our Creator in heaven. The window is only a means to assist supplicants in visualizing themselves standing in Jerusalem before the Almighty. As we look beyond our physical confines, we seek to journey through our prayers to holy spaces. The writer is on the faculty of Pardes Institute of Jewish Studies and is a rabbi in Tzur Hadassah.