There are a few isometric/perspective symbol sets that might help if you have the right add-ons or annuals.

CA149 Beaumaris Castle has both top-down and isometric symbols, including windows. You'll find the isometric symbols under:

C:\ProgramData\Profantasy\CC3Plus\Symbols\Perspectives\Castles\Beaumaris.

And if you have Perspectives, you may find more under the Bitmap A style:

C:\ProgramData\Profantasy\CC3Plus\Symbols\Perspectives\Bitmap A

Here is the second floor of the chapel.

I decided against adding an organ. I may save that for a large cathedral.

The floors here by the square towers are granite tiles, but then the rest is walnut planks. The left side of the transept, over the sacristy area of the first floor, has a choir room that can double as a scripture study classroom when the choir isn't using it for rehearsals. Next to it, the head priest has a private office.

On the right wing, there's a suite for the royal (or noble) family, where they can meet privately with honored guests before or after church services. A curtain separates the royal family's pews from the others on the balcony. This area is a little more removed, and doesn't have it's own stairs from the ground floor. The family would be escorted here using the stairs in the square towers. The That area can also serve as a bridal suite when used for high profile weddings.

In both transept areas, spiral staircases go up into the round towers. The windows here are all stained glass, more for visual continuity when looking at the chapel from the outside.

Actually, I didn't use fills for most of the grass except for a few areas to even out blotchiness. Mostly just the terrain patch symbols from Forest Trail.

First floor is done!

The entry area (the "narthex") uses one of my favorite brass inlays from Marine Dungeons. Left transept is the sacristy area. Small chamber for the head priest with a desk, wardrobe, small table. Another room with separate access to the nave is for the clergy to assemble and get into formation. Next to that is a room where they can socialize, and another dressing room for them. The right transept is has double wide stairs going down, because that provides access to the mortuary. Folks will be carrying coffins up those stairs! No stairs going up -- folks have to get to the balcony either from the spiral stairs near the entrance, or on the left side and then cross all the way around. And then there's a smaller side chapel. It uses the same winged statue used at the fountain.

Working on the interiors -- here's the first floor so far, plus zooming in on the apse. (Just noticed that one of my columns isn't lined up properly.)

The pews will continue up to the front. I'm thinking the transept (the side wings) will be closed off with interior walls, rather than fully open. That will let me create a sacristy and other areas on this floor.

Inside the apse, the pews on the sides could be for clergy on one side and the choir on the other, with the royal family seated either in the front row or the balcony. Or the choir could be moved to the balcony with the royal family seated in the choir section.

BTW, the cobblestone path in the graveyard looks like it dead ends at the wall of the chapel. It actually leads to a door going down to the basement. As this floor is elevated, the basement is only partially underground, with enough of the upper portions of the basement walls above ground, allowing for high, barred windows to let light in down there.

I really like how the smaller foothills provide texture to the terrain. Very nice.