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Stewart Plaza 400 N Mountain Ave 257 - 13,003 SF of Space Available in Upland, CA 91786

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HIGHLIGHTS

  • Elevator-served building with flexible office and medical layouts
  • Convenient location near 10 and 210 Freeways for regional connectivity
  • Executive suites available for turnkey occupancy
  • Heavy parking and easy access for staff and visitors
  • Surrounded by retail amenities for added convenience

ALL AVAILABLE SPACES(8)

Display Rental Rate as

  • SPACE
  • SIZE
  • TERM
  • RENTAL RATE
  • SPACE USE
  • CONDITION
  • AVAILABLE
  • 1st Floor, Ste 101
  • 2,800 SF
  • Negotiable
  • $33.00 /SF/YR $2.75 /SF/MO $92,400 /YR $7,700 /MO
  • Office/Medical
  • Shell Space
  • Now

Shell space available. Ideal For Office + Medical Uses. Surrounded by Many Retail Amenities. Executive Suites Available as well.

  • Rate includes utilities, building services and property expenses
  • Can be combined with additional space(s) for up to 5,974 SF of adjacent space
  • 1st Floor, Ste 104
  • 3,174 SF
  • Negotiable
  • $33.00 /SF/YR $2.75 /SF/MO $104,742 /YR $8,729 /MO
  • Office/Medical
  • Shell Space
  • Now

Shell space available. Ideal For Office + Medical Uses. Surrounded by Many Retail Amenities. Executive Suites Available as well.

  • Rate includes utilities, building services and property expenses
  • Can be combined with additional space(s) for up to 5,974 SF of adjacent space
  • 2nd Floor, Ste 211
  • 1,595 SF
  • Negotiable
  • $30.00 /SF/YR $2.50 /SF/MO $47,850 /YR $3,988 /MO
  • Office
  • Full Build-Out
  • Now

2 Offices, Bullpen

  • Rate includes utilities, building services and property expenses
  • 3 Private Offices
  • Fully Built-Out as Standard Office
  • 2nd Floor, Ste 215
  • 1,815 SF
  • Negotiable
  • $30.00 /SF/YR $2.50 /SF/MO $54,450 /YR $4,538 /MO
  • Office
  • Full Build-Out
  • 30 Days

3 Offices, Bullpen

  • Rate includes utilities, building services and property expenses
  • 3 Private Offices
  • Fully Built-Out as Standard Office
  • 2nd Floor, Ste 233
  • 257 SF
  • Negotiable
  • $30.00 /SF/YR $2.50 /SF/MO $7,710 /YR $642.50 /MO
  • Office
  • Full Build-Out
  • Now
  • Rate includes utilities, building services and property expenses
  • Office intensive layout
  • Fully Built-Out as Standard Office
  • 2nd Floor, Ste 234
  • 257 SF
  • Negotiable
  • $30.00 /SF/YR $2.50 /SF/MO $7,710 /YR $642.50 /MO
  • Office
  • Full Build-Out
  • Now
  • Rate includes utilities, building services and property expenses
  • Office intensive layout
  • Fully Built-Out as Standard Office
  • 2nd Floor, Ste 249
  • 555 SF
  • Negotiable
  • $30.00 /SF/YR $2.50 /SF/MO $16,650 /YR $1,388 /MO
  • Office
  • Full Build-Out
  • 30 Days

Executive Suite

  • Rate includes utilities, building services and property expenses
  • 3 Private Offices
  • Fully Built-Out as Standard Office
  • 3rd Floor, Ste 300
  • 2,550 SF
  • Negotiable
  • $30.00 /SF/YR $2.50 /SF/MO $76,500 /YR $6,375 /MO
  • Office/Medical
  • Full Build-Out
  • Now

Built-out medical space available. Reception, 5 Exam Rooms, Lab, Breakroom, Nurses Station, Doctor's Office. Elevator Served. Surrounded by Many Retail Amenities. Executive Suites Available as well.

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Medical Space
Space Size Term Rental Rate Space Use Condition Available
1st Floor, Ste 101 2,800 SF Negotiable $33.00 /SF/YR $2.75 /SF/MO $92,400 /YR $7,700 /MO Office/Medical Shell Space Now
1st Floor, Ste 104 3,174 SF Negotiable $33.00 /SF/YR $2.75 /SF/MO $104,742 /YR $8,729 /MO Office/Medical Shell Space Now
2nd Floor, Ste 211 1,595 SF Negotiable $30.00 /SF/YR $2.50 /SF/MO $47,850 /YR $3,988 /MO Office Full Build-Out Now
2nd Floor, Ste 215 1,815 SF Negotiable $30.00 /SF/YR $2.50 /SF/MO $54,450 /YR $4,538 /MO Office Full Build-Out 30 Days
2nd Floor, Ste 233 257 SF Negotiable $30.00 /SF/YR $2.50 /SF/MO $7,710 /YR $642.50 /MO Office Full Build-Out Now
2nd Floor, Ste 234 257 SF Negotiable $30.00 /SF/YR $2.50 /SF/MO $7,710 /YR $642.50 /MO Office Full Build-Out Now
2nd Floor, Ste 249 555 SF Negotiable $30.00 /SF/YR $2.50 /SF/MO $16,650 /YR $1,388 /MO Office Full Build-Out 30 Days
3rd Floor, Ste 300 2,550 SF Negotiable $30.00 /SF/YR $2.50 /SF/MO $76,500 /YR $6,375 /MO Office/Medical Full Build-Out Now

1st Floor, Ste 101

Size
2,800 SF
Term
Negotiable
Rental Rate
$33.00 /SF/YR $2.75 /SF/MO $92,400 /YR $7,700 /MO
Space Use
Office/Medical
Condition
Shell Space
Available
Now

1st Floor, Ste 104

Size
3,174 SF
Term
Negotiable
Rental Rate
$33.00 /SF/YR $2.75 /SF/MO $104,742 /YR $8,729 /MO
Space Use
Office/Medical
Condition
Shell Space
Available
Now

2nd Floor, Ste 211

Size
1,595 SF
Term
Negotiable
Rental Rate
$30.00 /SF/YR $2.50 /SF/MO $47,850 /YR $3,988 /MO
Space Use
Office
Condition
Full Build-Out
Available
Now

2nd Floor, Ste 215

Size
1,815 SF
Term
Negotiable
Rental Rate
$30.00 /SF/YR $2.50 /SF/MO $54,450 /YR $4,538 /MO
Space Use
Office
Condition
Full Build-Out
Available
30 Days

2nd Floor, Ste 233

Size
257 SF
Term
Negotiable
Rental Rate
$30.00 /SF/YR $2.50 /SF/MO $7,710 /YR $642.50 /MO
Space Use
Office
Condition
Full Build-Out
Available
Now

2nd Floor, Ste 234

Size
257 SF
Term
Negotiable
Rental Rate
$30.00 /SF/YR $2.50 /SF/MO $7,710 /YR $642.50 /MO
Space Use
Office
Condition
Full Build-Out
Available
Now

2nd Floor, Ste 249

Size
555 SF
Term
Negotiable
Rental Rate
$30.00 /SF/YR $2.50 /SF/MO $16,650 /YR $1,388 /MO
Space Use
Office
Condition
Full Build-Out
Available
30 Days

3rd Floor, Ste 300

Size
2,550 SF
Term
Negotiable
Rental Rate
$30.00 /SF/YR $2.50 /SF/MO $76,500 /YR $6,375 /MO
Space Use
Office/Medical
Condition
Full Build-Out
Available
Now

1st Floor, Ste 101

Size 2,800 SF
Term Negotiable
Rental Rate $33.00 /SF/YR
Space Use Office/Medical
Condition Shell Space
Available Now

Shell space available. Ideal For Office + Medical Uses. Surrounded by Many Retail Amenities. Executive Suites Available as well.

  • Rate includes utilities, building services and property expenses
  • Can be combined with additional space(s) for up to 5,974 SF of adjacent space

1st Floor, Ste 104

Size 3,174 SF
Term Negotiable
Rental Rate $33.00 /SF/YR
Space Use Office/Medical
Condition Shell Space
Available Now

Shell space available. Ideal For Office + Medical Uses. Surrounded by Many Retail Amenities. Executive Suites Available as well.

  • Rate includes utilities, building services and property expenses
  • Can be combined with additional space(s) for up to 5,974 SF of adjacent space

2nd Floor, Ste 211

Size 1,595 SF
Term Negotiable
Rental Rate $30.00 /SF/YR
Space Use Office
Condition Full Build-Out
Available Now

2 Offices, Bullpen

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Office
  • 3 Private Offices

2nd Floor, Ste 215

Size 1,815 SF
Term Negotiable
Rental Rate $30.00 /SF/YR
Space Use Office
Condition Full Build-Out
Available 30 Days

3 Offices, Bullpen

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Office
  • 3 Private Offices

2nd Floor, Ste 233

Size 257 SF
Term Negotiable
Rental Rate $30.00 /SF/YR
Space Use Office
Condition Full Build-Out
Available Now

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Office
  • Office intensive layout

2nd Floor, Ste 234

Size 257 SF
Term Negotiable
Rental Rate $30.00 /SF/YR
Space Use Office
Condition Full Build-Out
Available Now

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Office
  • Office intensive layout

2nd Floor, Ste 249

Size 555 SF
Term Negotiable
Rental Rate $30.00 /SF/YR
Space Use Office
Condition Full Build-Out
Available 30 Days

Executive Suite

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Office
  • 3 Private Offices

3rd Floor, Ste 300

Size 2,550 SF
Term Negotiable
Rental Rate $30.00 /SF/YR
Space Use Office/Medical
Condition Full Build-Out
Available Now

Built-out medical space available. Reception, 5 Exam Rooms, Lab, Breakroom, Nurses Station, Doctor's Office. Elevator Served. Surrounded by Many Retail Amenities. Executive Suites Available as well.

  • Rate includes utilities, building services and property expenses
  • Fully Built-Out as Standard Medical Space

PROPERTY OVERVIEW

Stewart Plaza offers a prime office and medical environment in the heart of Upland, CA. This professionally managed property features elevator service, abundant parking, and flexible suite sizes ranging from compact executive offices to expansive medical layouts. Tenants benefit from proximity to major transportation corridors, including the 10 and 210 Freeways, ensuring seamless regional connectivity. The surrounding area is rich with retail amenities, creating a convenient and vibrant setting for employees and clients alike. Medical professionals will appreciate suites designed with exam rooms, labs, and nurse stations, while traditional office users can select spaces with reception areas, private offices, and collaborative bullpens. Executive suites are also available for businesses seeking a turnkey solution. The property’s strategic location near Montclair, Ontario, and Claremont positions tenants within a dynamic Inland Empire market known for strong demographics and growth potential.

  • Atrium
  • Signage

PROPERTY FACTS

Building Type
Office
Year Built/Renovated
1987/2021
Building Height
3 Stories
Building Size
47,850 SF
Building Class
B
Typical Floor Size
15,950 SF
Unfinished Ceiling Height
12’
Parking
140 Surface Parking Spaces
Surface Tandem Parking
Covered Parking
Covered Tandem Parking
Reserved Parking
Walk Score®
Very Walkable (76)
What is a Walk Score®, Transit Score® & Bike Score®?
Walk Score® measures the walkability of any address.
Transit Score® measures access to public transit.
Bike Score® measures bikeability of a location.
What is a Walk Score®
, Transit Score® & Bike Score?
Walk Score® measures the walkability
of any address. Transit Score®
measures access to public transit. Bike Score®
measures bikeability of a location.®
  • Listing ID: 29858508

  • Date on Market: 1/7/2026

  • Last Updated:

  • Address: 400 N Mountain Ave, Upland, CA 91786

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