The marble main altar in the Bernardine convent church of St. Michael the Archangel in Wilno (Vilnius) is the largest architectural structure (the original height totalling 14.5 metres) raised from valuable material preserved up to our times in the former Commonwealth of Two Nations. In its present-day, secondary shape it constitutes in Polish art from the first half of the seventeenth century an exceptional example of a creative combination of two parts, stylistically and formally totally distinct, into a single architectural structure. The original Late Renaissance architectural structure founded prior to 1620 by Lew Sapieha, the voivode of Wilno (Vilnius), chancellor and grand hetman of Lithuania, was made with Pinczów limestone and decorative, colourful varieties of Checiny limestone by an unidentified workshop in Checiny. After the expansion of the church (1620-1625 to 1627) the founder decided to transform the structure of the altar, a feat accomplished in the summer of 1629 by unnamed Lutheran masons. The selection of costly material - several decorative varieties of Meuse limestone and marble - as well as the Protestant confession of the artists indicate that they could have been members of the large Low Countries colony in Wilno. One of its representatives was the renowned sculptor and mason Jan Filipin Wallon. The above mentioned expansion led to the erection of a monumental three-pening triumphal arch on which the structure of the earlier alter was placed, thus creating a narrower, two-storey crowning, decorated with a set of figures. During the course of repairing the church after the damage incurred by a Muscovite invasion (1663-1673) a new altar frame was added; its size was adapted to the new altar canvases purchased by the founders: Pawel Sapieha and prioress Konstancja Sokolinska. In the light of the above presented evidence the WiIno altar in its original form may be recognised as probably the earliest example of masonry and sculpture imported from Checiny to the Grand Duchy of Lithuania. The authorship of the project of the lower part of the altar (1629) remains unresolved, although we may assume that Lew Sapieha used a project devised by a professional architect-designer, who resorted rather to Late Renaissance forms than to the Early Baroque. The outcome of studies justify the conclusion that the analysed foundations of Lew Sapieha emerged almost during the same period as the analogous, from the viewpoint of style and form, examples of small architecture and sculpture in the Crown.