Järlåsa Church has had at least two predecessors. The earliest one was a medieval stone church whose ruins still remains c. 500 metres north of the church. At some point it was replaced with a wooden church, which was however in such a bad shape in the 17th century that it was replaced with the presently visible, octagonal church and demolished in the early 18th century.
The church may have been designed by Nicodemus Tessin the Elder; it was built at the initiative of Baron Gustaf Rosenhane, who is documented with having employed Tessin for other building projects. The main, octagonal church building was built 1672-1688 and inaugurated on 29 June 1688, while the church porch wasn't finished until 1704. Originally the sacristy was a wooden annex but it was replaced with a stone structure in 1766–68.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.