This is a 32x32x32 black marble pyramid you can build in vanilla Valheim. This is the tallest you can go from flat ground level. I have another pyramid with the actual 1/4 spires for a peak but it has to be a few levels lower as the 1/4 spires need much more support. I plan to work on building one even taller than this by manipulating the ground level around the supports to see how tall you can actually build a pyramid. Someone else also noted maybe using a pine tree in the center as anything attached to that is grounded, so I may play with that idea when I get some time.

Material requirements
584 Wood
292 Iron
9428 Black Marble
20 Yggdrasil Wood
10 Black Metal
5 Black Core
5 Refined Eitr

A pyramid of this size can also be seen on Jiroc's Runelands server where it is my temporary base until I finish my other mountain side / cliff base.

As you can see from the video there is plenty of room in the pyramid for everything to be built as well as having multiple levels above the lower level if needed or wanted.

If anyone has any ideas for similar builds they would like to see let me know and I can work on them or come with how to build them. I am working on a build video showing all of the maximum heights of different materials and what can be done to build even higher, as well as populating an excel sheet for quick reference. Hopefully I can get that done in the next couple weeks.