AL SOUTH BOSTON OWNER 1 LLC
33 office properties in Seattle / King County recorded to 7 owner entities mailing to PO BOX 847, CARLSBAD, CA. shared mailing address
At a glance
AL SOUTH BOSTON OWNER 1 LLC is recorded as the owner of 33 office properties (33 parcels) in Seattle / King County, totalling 6.2M sq ft of building area with $1.9B of assessed value. The holdings sit in 7 owner entities that share one tax-bill mailing address in CARLSBAD, CA — evidence of common ownership, not proof of it.
County assessment roll
Properties
| Building | Submarket | Sq ft | Assessed | Last sold | Tenants |
|---|---|---|---|---|---|
| 555 110TH AVE NE | Seattle | 1.1M | $160.8M | — | 0 |
| 12920 SE 38TH PL | Seattle | 555.9K | $66.5M | $467,500,000 · Apr 2019 | 0 |
| 3650 131ST AVE SE | Seattle | 546.3K | $47.5M | $467,500,000 · Apr 2019 | 0 |
| 3655 131ST AVE SE | Seattle | 468.8K | $36.6M | $467,500,000 · Apr 2019 | 0 |
| 1550 NE TURING ST | Seattle | 462.8K | $72.5M | $225,000,000 · Sep 2025 | 0 |
| 3617 131ST AVE SE | Seattle | 385.3K | $32M | $467,500,000 · Apr 2019 | 0 |
| 1621 N 34TH ST | Seattle | 336.3K | $81.2M | $219,975,000 · Nov 2021 | 3 |
| 3625 132ND AVE SE | Seattle | 323.6K | $38.8M | $467,500,000 · Apr 2019 | 0 |
| Epa Bldg | Denver | 303.8K | $119.3M | — | 0 |
| 201 ELLIOTT AVE W | Seattle | 202.4K | $100.9M | — | 5 |
| 1101 WESTLAKE AVE N | Seattle | 185.1K | $40.7M | $151,500,000 · Apr 2022 | 0 |
| 500 FAIRVIEW AVE N | Seattle | 167.2K | $89.7M | — | 3 |
| 7400 66TH AVE NE | Seattle | 110.7K | $36.5M | $58,000,000 · Dec 2024 | 0 |
| 10525 WILLOWS RD NE | Seattle | 97.1K | $36.7M | $135,996,730 · Aug 2018 | 0 |
| 3255 160TH AVE SE | Seattle | 95.7K | $20.3M | $43,000,000 · Nov 2019 | 0 |
| 3265 160TH AVE SE | Seattle | 95.3K | $17.9M | $43,000,000 · Nov 2019 | 0 |
| 1513 5TH AVE | Seattle | 88.7K | $26.1M | — | 0 |
| 1513 5TH AVE | Seattle | 76.5K | $18.1M | — | 0 |
| 10915 WILLOWS RD NE | Seattle | 67.6K | $25.5M | $135,996,730 · Aug 2018 | 0 |
| 10865 WILLOWS RD NE | Seattle | 67.6K | $25.4M | $135,996,730 · Aug 2018 | 0 |
| 5800 MESA DR 325 | Houston | 53.5K | $26.6M | — | 0 |
| 10545 WILLOWS RD NE | Seattle | 50.9K | $19.1M | $135,996,730 · Aug 2018 | 0 |
| 10785 WILLOWS RD NE | Seattle | 50.3K | $18.8M | $135,996,730 · Aug 2018 | 0 |
| 10675 WILLOWS RD NE | Seattle | 50.1K | $18.6M | $135,996,730 · Aug 2018 | 0 |
| 10735 WILLOWS RD NE | Seattle | 43.9K | $16.3M | $135,996,730 · Aug 2018 | 0 |
| 3106 160TH AVE SE | Seattle | 39K | $7.4M | $31,000,000 · Nov 2019 | 0 |
| 1600 FAIRVIEW AVE E | Seattle | 37.6K | $6.9M | — | 0 |
| 3076 160TH AVE SE | Seattle | 35.8K | $7.7M | $31,000,000 · Nov 2019 | 0 |
| 18 22 W THIRD ST | Boston | 34.5K | $3.6M | $11,500,000 · Jun 2018 | 0 |
| 96 Thirteenth ST | Boston | 25.3K | $7.6M | — | 0 |
| 8991 SW 107 AVE | Kendall | 9.8K | $2.6M | $88,500,000 · Mar 2007 | 2 |
| 906 ADAMSON ST SW | Atlanta | 6.4K | — | — | 0 |
| 3 BLACKFAN CI TOWER | Boston | 1 | $647.8M | — | 0 |
Names on the deeds
Owner entities at this address
- DENVER EPA OC LLC
- LBA NCC-COMPANY XXXI LLC C/O LBA REALTY
- AL SOUTH BOSTON OWNER 1 LLC
- ARE-79-96 CHARLESTOWN NAVY
- SVF KENDALL MIAMI LLC
- REGIONAL RECYCLING L L C
- BMR-BLACKFAN CIRCLE LLC
How this group was built. These entities share a mailing address but not a name root. That often means one sponsor, and can also mean a shared law firm, accountant or tax servicer.The county records an owner and a mailing address for every parcel; this page collects the office parcels whose owners mail to the same address, and counts buildings rather than parcels using the county's own condo-to-building link. Lease terms, rents and the identity of a manager acting for the owner are not public records and are not shown.
Where are AL SOUTH BOSTON OWNER 1 LLC's office buildings?
The 33 properties are spread across 6 cities, led by Seattle (26), Boston (3), Denver (1).
The largest is 555 110TH AVE NE in Seattle at 1.1M sq ft over 26 floors.
Recorded build years run from 1899 to 2020.
How large is this portfolio within Seattle's office market?
Its 6.2M sq ft is 3.09% of the 200.1M sq ft of office building area on the Seattle / King County roll.
Its $1.9B of assessed value is 4.08% of the metro's office total.
It holds 33 of the metro's 4,289 office buildings.
22 of its parcels carry a recorded sale price; the most recent was 1550 NE TURING ST in Sep 2025 for $225,000,000.
Frequently asked questions
How many office buildings does AL SOUTH BOSTON OWNER 1 LLC own in Seattle?
33 office properties (33 parcels) on the Seattle / King County roll, counted by building rather than by condo parcel.
What is AL SOUTH BOSTON OWNER 1 LLC's largest office building?
555 110TH AVE NE, Seattle — 1.1M sq ft, assessed at $160.8M.
What are AL SOUTH BOSTON OWNER 1 LLC's office properties worth?
Their combined assessed value on the current Seattle / King County roll is $1,876,008,719. Assessed values are taxable-roll figures, not market prices.
Are these properties owned by one company?
These entities share a mailing address but not a name root. That often means one sponsor, and can also mean a shared law firm, accountant or tax servicer. 7 owner entities share the mailing address. It is evidence of common ownership, not proof of it.
When did one of AL SOUTH BOSTON OWNER 1 LLC's Seattle office properties last change hands?
The most recent recorded transfer among these parcels is 1550 NE TURING ST, Sep 2025, for $225,000,000.
Related
Everything here comes from public records, and public records go stale. If you know better, say so.
Data provenance — public records only
- Seattle / King County — King County Assessor bulk extracts and Seattle open data. Washington law restricts commercial use of lists of individuals, so this metro is built without personal names by design: the county's name-stripped account file provides mailing addresses (portfolios group by mailing cluster, unnamed), sales show price and date but never buyer or seller, and tenants are business licence trade names.
Every fact on this page is drawn from the government records above — no listing sites, no scraped platforms, no third-party images. Facts from public records are uncopyrightable; each tenancy row carries its source and match confidence. Records can lag reality — a business-tax receipt or registration at an address is evidence of occupancy, not a lease confirmation.
Dataset updated . Derived from public data sources.
About this data
Source: King County Assessor bulk extracts and Seattle open data (Seattle / King County), as published October 8, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: BuildingCensus, “AL SOUTH BOSTON OWNER 1 LLC — Seattle office property holdings”, https://buildingcensus.com/offices/seattle/owners/al-south-boston-owner-1-llc-843dfb (data as of October 8, 2026).