that followed in the fifteenth century. Muscovite masonry continued to develop in the fifteenth and early sixteenth century, with the production of brick being more apparent in the mid-fifteenth century. In 1474 Ivan III imported builders from Pskov to Moscow (Pskov had been saved from ruin by the Mongol horde, and thus had more advanced construction knowledge than Moscow), and they adapted the stone-slab method of construction from Pskov to the brick masonry of the churches that followed as well as incorporating several features characteristic of churches in Pskov, such as corbel arches, church porches, exterior galleries, and bell towers. The brick construction as well as a new Muscovite tendency towards bold architectural ornament is featured in the Church of the Holy Spirit (1476) which has an frieze created by glazed ceramic tiles, deriving from the ornamental stripes of Novgorod, Pskov, and Suzdalia. Other churches built by the Pskov builders during this period show more influence from Pskov's style, such as ornamental brickwork in the façade of the Church of the Deposition of the Robe (1484-5). Apart from churches, many other structures date from Ivan III's reign. These include fortifications (Kitai-gorod, the Kremlin (its current towers were built later), Ivangorod), towers (Ivan the Great Bell Tower) and palaces (the Palace of Facets and the Uglich Palace). In the 16th century, the key development was the introduction of the tented roof in brick architecture. It is believed that this Russian derivation is a continuation of the manner of wood construction being taken in masonry form, and is a form that completely deviates from the accepted Orthodox forms. The first tent-like brick church is the Ascension church in Kolomenskoe (1531), designed to commemorate the birth of Ivan the Terrible. Its design gives rise to speculation; it is likely that this style (never found in other Orthodox countries) symbolized the ambition of the nascent Russian state and the liberation of Russian art from Byzantine canons after the Fall of Constantinople to the Turks. The style of church was also known as “Tower Churches”. After the Time of Troubles the church and state were bankrupt, unable to finance any construction works; an initiative was taken by rich merchants in Yaroslavl, on the Volga. During the 17th century, they built many large cathedral-type churches with five onion-like domes, surrounding them with tents of bell towers and aisles. At first the churches' composition was sharply asymmetrical,