601 Massachusetts Avenue
Office (large) · Washington · 20001 · 601 MASSACHUSETTS AVE NW
At a glance
601 Massachusetts Avenue (601 MASSACHUSETTS AVE NW) in Washington, DC is listed on the Washington, DC property roll as “Office (large)”, SSL 0484W0025. The roll records 526,768 sq ft of building area, a 2015 build year and an assessed value of $281,000,000. It last sold for $531,000,000 in Aug 2022. 8 active business locations at this address appear in public records.
The building's own benchmarking filing
Energy performance
From the building's own filing under its city's benchmarking ordinance, latest of 2 years on record. An ENERGY STAR score of 75 or above means the building outperforms three quarters of comparable buildings nationally. It is a self-reported figure, verified by the city only to the extent the ordinance requires.
Recorded transfers — county roll + state sale file
Sale history
| Recorded | Price | Qualification | Source | Instrument |
|---|---|---|---|---|
| Aug 2022 | $531,000,000 | not rated | County roll | — |
Prices are the consideration recorded in Washington, DC's public property records. Where a qualification code exists it is the assessor's judgement of whether a transfer was arm's length; transfers without one appear unrated rather than assumed clean. Whether a building is on the market today, and at what price, is not a public record and is not shown here — asking prices, listings and lease terms live in private commercial databases.
Public record — 8 matched business locations
Tenants & business locations
| Company | Suite / floor | Since | Source | Match |
|---|---|---|---|---|
| N/A | — | Oct 2026 | DC business licence | folio match · high |
| ESA'S FOUNDATION | 300w | Mar 2026 | DC business licence | folio match · high |
| FLIK INTERNATIONAL CORPORATION | — | Feb 2026 | DC business licence | folio match · high |
| ENTERTAINMENT SOFTWARE ASSOCIATION | 300 | Mar 2025 | DC business licence | folio match · high |
| LAZ PARKING MID-ATLANTIC LLCvia LAZ PARKING MID-ATLANTIC LLC. | — | Feb 2025 | DC business licence | folio match · high |
| RPM ITALIAN/ CAFE 110 | — | Jan 2025 | DC business licence | folio match · high |
| HEALTHSPERIEN, | — | Jul 2024 | DC business licence | folio match · high |
| SWEETGREENvia Sweetgreen | — | Oct 2022 | DC business licence | folio match · high |
Washington, DC assessment roll
Parcel record
| Field | Value |
|---|---|
| SSL | 0484W0025 |
| Site address | 601 MASSACHUSETTS AVE NW |
| Land use (DOR) | 052 — Office (large) |
| Building area (actual) | 526,768 sq ft |
| Floors / units / buildings | — / — / — |
| Lot size | 44,918 sq ft |
| Year built | 2015 |
| Zoning (primary) | — |
| Land value | — |
| Building value | — |
| Total assessed value | $281,000,000 |
Recorded owner (assessment roll)
MT D.C. TWO LLC
Owner mailing address: 601 MASS AVE NW, WASHINGTON, DC, 20001
Location
- Address
- 601 MASSACHUSETTS AVE NW
- City
- Washington
- ZIP
- 20001
Within ~650 m
Nearby office buildings
No other office parcels within ~650 m.
How does 601 Massachusetts Avenue compare with other Washington office buildings?
At 526,768 sq ft, 601 Massachusetts Avenue is about 4 times the size of the average office building on the Washington, DC roll, which comes to 120,450 sq ft across 1,761 buildings.
Its assessed value works out to $533 per square foot of building area, against $370 across all office floor area on the roll.
The last recorded sale priced it at $1008 per square foot.
What has happened at 601 Massachusetts Avenue recently?
1 recorded transfer is on file for this parcel, the latest dated Aug 2022.
The building files energy-benchmarking disclosures — 2 report years are matched to this parcel.
What does “Office (large)” mean for this parcel?
The Washington, DC roll classifies SSL 0484W0025 as “Office (large)” (use code 052). BuildingCensus includes a parcel in its office census when the roll gives it an office-class use, so the label is the county's, not an inference.
Frequently asked questions
Who owns 601 Massachusetts Avenue?
The recorded owner on the Washington, DC assessment roll (current) is MT D.C. TWO LLC. Owner mailing address on file: 601 MASS AVE NW, WASHINGTON, DC, 20001.
What companies have offices at 601 Massachusetts Avenue?
8 active business locations at this building appear in Washington, DC public records, including N/A, ESA'S FOUNDATION, FLIK INTERNATIONAL CORPORATION, ENTERTAINMENT SOFTWARE ASSOCIATION, LAZ PARKING MID-ATLANTIC LLC. Public records under-count tenants that don't hold a local receipt or register the address.
How big is 601 Massachusetts Avenue?
The Washington, DC roll records 526,768 sq ft of building area, a build year of 2015. It sits on a 44,918 sq ft lot.
What is the assessed value of 601 Massachusetts Avenue?
$281,000,000 on the Washington, DC roll. Assessed values are taxable-roll figures, not market prices.
When did 601 Massachusetts Avenue last sell?
The last recorded transfer was in Aug 2022 for $531,000,000 ($1008 per square foot).
What is the SSL for 601 Massachusetts Avenue?
SSL 0484W0025, site address 601 MASSACHUSETTS AVE NW, Washington. It is the key to look the parcel up in the Integrated Tax System public extract (Washington, DC).
More around 601 Massachusetts Avenue
Everything here comes from public records, and public records go stale. If you know better, say so.
Data provenance — public records only
- Washington, DC — Integrated Tax System public extract (owner names, mailing addresses, assessments), CAMA commercial and daily sales tables, Basic Business Licenses (suite-level premises; the universal catch-all licence was repealed Oct 2025, thinning the roll thereafter), and DOEE energy benchmarking.
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.
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Dataset updated . Source: Washington, DC assessment roll, SSL 0484W0025.
About this data
Source: Integrated Tax System public extract (Washington, DC), as published September 20, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: BuildingCensus, “601 Massachusetts Avenue, Washington, DC (SSL 0484W0025)”, https://buildingcensus.com/offices/dc/601-massachusetts-avenue-e652be58 (data as of September 20, 2026).