Most of Tessin's projects as an architect were produced during the 17th century, including several churches such the King Charles' Church in Kungsör and the Holy Trinity Church in Karlskrona, and many of his proposals never were built.
Väčšina jeho projektov (ako architekta) boli vytvorené počas 17. storočia, vrátane niekoľkých kostolov, ako napr. kostol kráľa Karola v Kungsör a kostol sv. Trojice v Karlskrona, a mnoho z jeho návrhov nebolo nikdy realizovaných.