Started building a house but the lot was too small, so saved it to the library and removed it from that lot. Restarted that world, went to Edit Town and selected a larger lot, imported the house, placed it on that lot, centered it, okayed that and returned to build mode ....where the house is in a pit. Could find no way to raise the structure to ground level so accepted the challenge of finishing it as it sat and landscaping around it. But why did the house appear in a pit? (it was on level ground went built and exported) and is there a way to correct that?

Fwiw ......

You have to use a cheat to align the lot with street level when placing it via Edit Town.

First, bulldoze the house. Before placing it again press Ctrl+Shift+C, type "testingcheatsenabled true", hit Enter. Then, press Ctrl+Shift+C again and type "setimportedterrainoffset <value>". The value must be a number, and it can be positive/negative, or decimal like 1.5 (In your case it needs to be positive). If you don't get it right on the first try, you can keep retyping the cheat with different numbers until you get it right. Next, use "constrainfloorelevation off" to flatten and even out the lot if some parts get raised or sunken.

Once you are done placing this lot and want to place a normal one that isn't raised/sunken, set "setimportedterrainoffset" back to 0 so the height offset doesn't apply to your next lot.

EDIT: You could also use "constrainfloorelevation off" entirely but you have to redo the leveling of the floors and some objects can get raised above ground so you have to delete them and press CTRL+Z to return them, this time in their normal position

Thank you! I suspected some arcane command buried in the system.

I don't like this house (the top rooms have a wonderful view ....and a trek down four flights of spiral stairs to the bathrooms), though a friend deems it cool; it was designed as a feasibility study for a larger structure where each bedroom will be a small suite.

Actually it's not bad design and Iike it. It has potenial as futuristic/brutalism style home and you can make each bedroom suite little more bigger and change or include more furniture/decoration that fit better in this style from other EPs if possible (High-End loft stuff, Diesel or from Into The Future). Just be careful with the spiral staircase placement, because they are prone to create routing failures if they are not placed properly.

"Just be careful with the spiral staircase placement..."

A major issue since there are no double wide spiral stairs; if residents want to go to bed, or to the bathroom, at the same time, tempers will flare. (For some weird reason the stairs do not appear in screenshots.)

Spent an hour playing around with the terrain elevation; no idea what are its limits, doesn't seem linear, and is occasionally unpredictable. But it worked -

FWIW, I did use a pair of spiral staircases, on opposite corners of the central column, on an early "pedestal" house to access the pool/yard area; street access is via the lofty staircase on the left -