Vormsi is a small island that belonged to the Oesel-Wiek bishopric during the Middle Ages. There is a church on the island that is dedicated to St Olaf, the Norwegian king who was undoubtedly the most popular saint among the Scandinavians. A short article written by Villem Raam in the anthology Eesti Arhitektuur (Estonian Architecture, 1996) is the only one worth mentioning that has appeared to date on the architectural history of the Vormsi church.The Vormsi church is comprised of a sanctuary and nave. Only the sanctuary was completed during the Middle Ages, and the stone nave was not completed until 1632. During the restoration of the church between 1989 and 1990, fragments were found of the foundation of the wooden church that predated the stone one. It is possible that the wooden church was utilised throughout the Middle Ages as a congregation room.Currently, it is believed that the Vormsi sanctuary was built during the 15th century. This dating is based on the pyramid-shaped vault consoles – a similar shape also appears in the chapel of the gate tower in the Padise Cistercian monastery. Actually, the Padise consoles have been reused. Their original location is unknown and their completion is impossible to date even within the time frame of a century.The most significant is the eastern wall of the Vormsi sanctuary, where a spacious niche with pointed arch is located. This Cistercian composition was also used in the Haapsalu Cathedral and apparently that was the model for the Vormsi church. The Haapsalu Cathedral is a surprisingly simple single-nave church with three bays. The church has richly decorated capitals on its wall pillars, on which both Romanesque and Early Gothic motifs have been used. At least some of the capitals have been hewn by a master who previously worked on the construction of the capital hall in the Riga Cathedral. The northern section of the Haapsalu Cathedral was apparently built in the 1260s. In the vicinity of Riga there is a church with a floor plan that is an exact counterpart to the one in Haapsalu – the Holme / Martinsala Church that dates back to about the 13th century. Considering both the floor plan and the sculptured decorations, it is believable that the designers and builders of the Haapsalu Cathedral came from the Riga environs.Pärnu is also on the Riga-Haapsalu route. Actually, two towns existed there during the Middle Ages. For a short time, Old-Pärnu on the right bank of the river had been the centre of the Oesel-Wiek bishopric before Haapsalu. However, the left bank of the river was controlled by the Livonian Order. There is very little information about the Old-Pärnu Cathedral that was completed around 1251 and destroyed by the Lithuanians in 1263. However, one thing is known – it also had a single-nave with three bays. There is no information about the design of the eastern wall of the cathedral. However, the sanctuary of St Nicholas’ Church in New-Pärnu had an eastern niche similar to the one in Haapsalu. It is not impossible that the motif was borrowed from the cathedral across the river or its ruins. Attention should also be paid to the fact that the design of the northern and southern walls in the sanctuary of Pärnu’s St Nicholas’ Church are similar to the Vormsi church. Therefore, there is no doubt that these two sanctuaries are architecturally and genetically related. Apparently the Vormsi sanctuary was built immediately or soon after the completion of the Haapsalu Cathedral – not later than 1270. It is not impossible that the vaults were constructed sometime later.The vault painting in the Vormsi sanctuary is probably inspired by the “paradise vaults” in Gotland. The Vormsi painting is strikingly primitive. In Estonia, this primitive style can also be seen in the churches in Ridala and Pöide.There is a squint (hagioscope) on the southern wall of the Vormsi church sanctuary, and an unusual sacrament niche with a light shaft in the eastern wall. This does not date back to the time when the sanctuary was built, but was added later. There have been at least eight such sacrament niches in Estonia, most of which were built in the 15th century.