The ASAM Sensor MkII is the most advanced version of ASAM Sensor technology developed by Karl S. Magnusson. It is introduced in Chapter 3 during When It Rains.
The ASAM Sensor MkII can be used to upgrade an ASAM Sensor on an existing plot to build an Architectural Marvel Class building plan.
The ASAM Sensor MkII can be crafted at a City Planner's Desk and requires the following components:
Any Plot Type can have a building plan for an Architectural Marvel. Currently, Sim Settlements 2 has one building plan for an Architectural Marvel. That building plan is the [SS2C3] Helios Tower available only in SS2 Extended and is unlocked through completing a research project in Headquarters.
(See Epilogue: Bring Down the Sky.)
Building Plan mod authors can provide additional building plans that will likely have different requirements to unlock their Architectural Marvels.