The church is believed to have been designed by Archbishop Eystein Erlendsson. The first church at Stiklestad was built on the site where St. Olav fell in 1030. It is likely that a wooden church stood at Stiklestad before the stone church was built. But around the middle of the 12th century, the building of the chancel of the current church started. A portal surrounds the old vicar's entrance on the southern side, and you will find stylistic elements from the Anglo-Norman style as it was developed in England in the late 11th century. The oldest extension that stands today is the sacristy on the southern side of the church. The nave of the church is younger than the chancel as the nave on the southern side cannot have been carved until around 1200. This shows that the church stood for some time without a nave or an incomplete nave, but such long construction periods were common in the Middle Ages. The same kinds of chevrons (zigzag lines) feature on the southern entrance of the nave and southern entrance of the chancel. The circular arc is a variant of the zigzag lines, and it is framed by a slender gothic runner. The columns also show signs of early Gothic features. At some point during the Late Middle Ages the nave was extended towards the west by about 10 m. In the church, you can still see the distinction between the old and the new parts because the floor of the extension is slightly higher than in the original church. This can be attributed to mudslides. When the church was expanded, the western portal was taken down and rebuilt. Ornamentation on this portal is from the Late Romanesque period. Inside the porch, we can still see the old altarpiece, which dates from 1655. It is shaped in baroque style. It was built by Johan Bildhugger, and the altarpiece was originally painted by Johan Kontrafeier. Approx. 1870, it was painted over by the Swedish artist Erik Valne, and here as always he used a lot of white paint. Upon restoration in the years prior to 1930, unclear chalk paintings emerged on the long walls inside the nave. On the southern wall, you can see two painted coats of arms, the westernmost of which is the Norwegian coat of arms. The second contains several Nordic coat of arms and, as such, points to one of the union kings. In the nave, we also find 32 painted panels showing episodes from the life of Jesus. They are painted by Barach Bogarth from Trondheim in 1688, and he used the copper plate from Merian Bible edition (approx. 1630) as a basis.