When I installed LR, the Western sector of the city was floating in the air. Is this a mod problem, or is there something I have to do to get it to work?
If this is a mod problem, I will post my mod list. I have the most recent Unofficial Oblivion Patch.

Post your load order. You probably need to load it later in your load order or something. Do you use BOSS? You should get it now. It does not matter how few mods you are using.

http://sites.google.com/site/oblivionpoinfo/finishinstall/loadorder <-- link to BOSS toward the bottom, but you may want to read the rest as well

Oblivion.esm
MERP Data.esm
MiddleEarth.esm
CM Partners.esm
underdark.esm
Cobl Main.esm
CyrodiilUpgradeResourcePack.esm
TR_OoT_Main.esm
Open Cities Resources.esm
MERP Patch.esp
Cobl Glue.esp
Cobl Si.esp
Cobl Tweaks.esp
Unofficial Oblivion Patch.esp
DLCHorseArmor.esp
CM Partners.esp
Oblivion Citadel Door Fix.esp
Cobl Races.esp
Cobl Races TNR.esp
Cobl Races TNR SI.esp
DLCOrrery.esp
DLCVileLair.esp
fadingtorches v1.3b.esp
DLCHorseArmor-HC2.2nightmare.esp
_darker_dungeons.esp
Salmo the Baker, Cobl.esp
Real Lava v1.2.esp
_darker_nights_for_nat_env.esp
DLCFrostcrag.esp
DLCThievesDen.esp
DLCMehrunesRazor.esp
DLCSpellTomes.esp
Knights.esp
M.O.E. - New Classes.esp
M.O.E. - Mythic Dawn Powers.esp
M.O.E. - Playable Dremora and Custom Race Fix.esp
M.O.E. - Unlocked Hairstyles.esp
M.O.E. - Levitation Magic.esp
M.O.E. - Playable Scythe.esp
DLCShiveringIsles.esp
MaleBodyReplacerV3.esp
DLCBattlehornCastle.esp
M.O.E. - Unlocked Palace Guard Armour.esp
M.O.E. - Unlocked Glenroy and Captain Renault Blades Armour.esp
M.O.E. - Unlocked Dremora Armour and Robes.esp
Castle_Dunkerlore_V1.esp
M.O.E. - Lucien Lachance Rumors Fix.esp
M.O.E. - Bone Names and Priced Skull.esp
Ring of console.esp
300_White Stallion 4.esp
Symphony of Violence.esp
Servant of the Dawn.esp
M.O.E. - Lycanthropy and Lichcraft.esp
M.O.E. - Travel Services.esp
WOTFH_1.3.esp
road+bridges.esp
TR_Stirk.esp
RTFemaleReplacerV12.esp
tda_Armoury.esp
P1DseeYouSleep.esp
P1DseeYouSleep - DLCVileLair.esp
West Roads.esp
Open Cities Full.esp
Open Cities Outer Districts.esp
IOM - Arena.esp
KvatchAftermath.esp
Natural_Weather_HDR_by_Max_Tael.esp
Natural_Vegetation_by_Max_Tael.esp
MERP Travel Spells.esp
Natural_Habitat_by_Max_Tael.esp
(DC) Sutch Reborn.esp
MERP Armoury Chest.esp
Natural_Water_by_Max_Tael.esp
TRoN.esp
IOM - Kvatch.esp
IOM - Main Quest.esp
Guards.esp
Slof's Horses HA Essential.esp
TitanOfEther - Vestments of the Steward-Prince.esp
The Ayleid Steps.esp
RealisticForceLow.esp
RealisticMagicForceLow.esp
NRB4 Standard Road Record.esp
Cobl Races - Balanced.esp

I do use OBMM.

I asked if you use BOSS, not OBMM...Follow the "Load Ordering" link in my previous poast.

http://sites.google.com/site/oblivionpoinfo/stabilization/stabilizationmods <-- see section near bottom
http://sites.google.com/site/oblivionpoinfo/stabilization/outdatedmods

I had funky land, some stuff floating, other stuff buried when I first installed Leyawiin Reborn. Others have reported similar problems.

What fixed it for me was blindingly simple. I traveled away from the area, waited for 3 days then returned. Everything was as it should be.

got to be worth a try.

Nevertheless, you should still use BOSS and read the BOSS log as well.

Edit. First attempt was unintelligable

Thank you, that fixed it faster than I could blink!

Yay! There has been so much progress today, big smiles all around!