**Exhibit 21**    **Subsidiary Name** **Organization** 7158 Willoughby, LLC     Delaware    AICP LLC     Delaware    Alban Towers L.L.C.      DC    AMERITON Properties Incorporated     Maryland    API Barrington Hills, LLC     Delaware    API Cameron Park LLC     Delaware    API Dadeland LLC     Delaware    API Fox Plaza LLC     Delaware    API Genesis Park LLC     Delaware    API Hibiscus LLC     Delaware    API Highland Lake Incorporated     Delaware    API Kentlands Incorporated     Delaware    API Lakemont LLC     Delaware    API Laurel Crossing LLC     Delaware    API Mission North LLC     Delaware    API Multifamily Properties LLC     Delaware    API Rio Salado LLC     Delaware    API Roosevelt Center Incorporated     Delaware    API Sonoma Incorporated     Delaware    API Stratford LLC     Delaware    Archstone Financial Services LLC     Delaware    Archstone Foundation     Delaware    Archstone Management Services    Incorporated     Delaware    Archstone Property Management    (California) Incorporated     Delaware    Archstone Property Management LLC     Delaware    Archstone Smith Unitholder    Services LLC     Delaware    Archstone Vinnin Square LLC     Delaware    Archstone-Smith Communities LLC     Delaware    Archstone-Smith Trust     Maryland    ASN 50th Street LLC     Delaware    ASN Aston LLC     Delaware    ASN Bell Lakes LLC     Delaware    ASN Bellevue LLC     Delaware    ASN Bowie LLC     Delaware    ASN Calabasas I LLC     Delaware    ASN Calabasas II LLC     Delaware    ASN Cambridge LLC     Delaware    ASN Chelsea LLC     Delaware    ASN Chicago LLC     Delaware    ASN City Place LLC     Delaware    ASN Clinton Green Member LLC     Delaware    ASN Cypress Cove LLC     Florida    ASN Dakota Ridge LLC     Delaware    ASN Doral West LLC     Florida    ASN Dupont Circle LLC     Delaware    

 
   **Subsidiary Name** **Organization** ASN Estancia     Delaware    ASN Europe NPL Incorporated     Delaware    ASN Europe NPL LLC     Delaware    ASN Fairfax Corner LLC     Delaware    ASN Falls Church LLC     Delaware    ASN Foundry LLC     Delaware    ASN Fox Plaza LLC     Delaware    ASN Gaithersburg LLC     Delaware    ASN Gresham Commons LLC     Delaware    ASN Hoboken I LLC     Delaware    ASN Hoboken II LLC     Delaware    ASN Holdings LLC     Delaware    ASN Kendall Square LLC     Delaware    ASN LaJolla LLC     Delaware    ASN Lakeshore East LLC     Delaware    ASN Las Colinas LLC     Delaware    ASN Las Flores LLC     Delaware    ASN Long Beach LLC     Delaware    ASN Los Feliz LLC     Delaware    ASN Maple Leaf (Office) LLC     Delaware    ASN Maple Leaf Member LLC     Delaware    ASN Marina Del Rey LLC     Delaware    ASN Marina LLC     Delaware    ASN Meadow Wood LLC     Delaware    ASN Miramar Lakes LLC     Delaware    ASN Mission Center LLC     Delaware    ASN Mountain View LLC     Delaware    ASN Multifamily Limited Partnership     Delaware    ASN Newport Crossing LLC     Delaware    ASN Northgate LLC     Delaware    ASN OEC Incorporated     Delaware    ASN Palm Trace Landings LLC     Delaware    ASN Paradise Lakes LLC     Delaware    ASN Park Essex LLC     Delaware    ASN Pasadena LLC     Delaware    ASN Pinnacle LLC     Delaware    ASN Portofino LLC     Delaware    ASN Presidio View LLC     Delaware    ASN Reading LLC     Delaware    ASN Redmond LLC     Delaware    ASN Redmond Park LLC     Delaware    ASN Regency Club LLC     Delaware    ASN RH Member LLC     Delaware    ASN Richardson Highlands LLC     Delaware    ASN Rockville LLC     Delaware    ASN Rolling Hills Manager LLC     Delaware    

 
   **Subsidiary Name** **Organization** ASN Roosevelt Center LLC     Delaware    ASN San Diego LLC     Delaware    ASN San Jose LLC     Delaware    ASN Santa Monica LLC     Delaware    ASN Saybrooke LLC     Delaware    ASN Seattle LLC     Delaware    ASN Shadowood LLC     Delaware    ASN Sonoma LLC     Delaware    ASN StoneRidge LLC     Delaware    ASN StoneRidge Manager LLC     Delaware    ASN Studio City LLC     Delaware    ASN Summit LLC     Delaware    ASN Sussex Commons LLC     Delaware    ASN Symphony Place LLC     Delaware    ASN Technologies, Inc.      Delaware    ASN Texas GP LLC     Delaware    ASN Ventura LLC     Delaware    ASN Virginia Holdings LLC     Delaware    ASN Walnut Creek LLC     Delaware    ASN Warner Center LLC     Delaware    ASN Washington Boulevard LLC     Delaware    ASN Watertown LLC     Delaware    ASN Wendemere LLC     Delaware    ASN West End LLC     Delaware    ASN Wisconsin Place (Residential)    LLC     Delaware    ASN Wisconsin Place (Retail) LLC     Delaware    ASN Woodland Hills East LLC     Delaware    ASN-Massachusetts    Holdings (1) LLC     Delaware    ASN-Massachusetts    Holdings (2) LLC     Delaware    ASN-Massachusetts    Holdings (3) LLC     Delaware    ASN-Massachusetts    Holdings (4) LLC     Delaware    ASN-Massachusetts    Holdings (5) LLC     Delaware    ASN-Washington    Holdings (1) LLC     Delaware    Brandywine Apartments of Maryland,    LLC     Delaware    Capital Mezz LLC     Delaware    Casco Dunwoody LLC     Delaware    Casco GP LLC     Delaware    Casco Properties LP     Delaware    Casco Property Trust LLC     Delaware    Casco TN GP Inc.      Delaware    Casco TN LP     Delaware    Chateau Marina LLC     Delaware    Chateau Marina, L.P.      California    Courthouse Hill L.L.C.      Delaware    Detriot Village LLC     Delaware    Fiji Villas, LLC     Delaware    

 
   **Subsidiary Name** **Organization** First Herndon Associates Limited    Partnership     Delaware    First Multifamily Properties LLC     Delaware    Golden State Mezz LLC     Delaware    Hacienda Cove, LLC     Florida    Interlocken Apartments LLC     Delaware    Katahdin GP LLC     Delaware    Katahdin Properties LP     Delaware    Katahdin Property (Colorado), LLC     Delaware    Katahdin Property Trust LLC     Delaware    KV Construction Incorporated     Delaware    La Brea Gateway LLC      Las Palmas LLC     Florida    Metropolitan Acquisition Finance LP     Delaware    MIV (2) LLC     Delaware    Monadnock Property Trust, LLC     Delaware    Monadnock Texas LP     Texas    Monterey Ranch Residential and    Commercial Community Property Owners’ Association Inc.      Texas    MP North Carolina GP Inc.      Delaware    MP North Carolina LP     Delaware    Museum Gardens LLC     Delaware    Northblock Lofts, LLC      Panorama Insurance Ltd.      Bermuda    PTR-California    Holdings (1) LLC     Delaware    PTR-California    Holdings (3) LLC     Delaware    PTR-Colorado (1) LLC     Delaware    R&B Realty Group II, LLC     Delaware    SCA Florida    Holdings (2) LLC     Delaware    SCA-North    Carolina (2) LLC     Delaware    SCA North Carolina Limited    Partnership     Delaware    SCA-North    Carolina (1) LLC     Delaware    Second Multifamily Properties LLC     Delaware    Second Multifamily Properties LP     Texas    Security Capital Atlantic    Multifamily LLC     Delaware    Smith Property Holdings 2000    Commonwealth L.L.C.      Delaware    Smith Property Holdings 4411    Connecticut Avenue LLC     Delaware    Smith Property Holdings Alban    Towers L.L.C.      Delaware    Smith Property Holdings Alban    Towers Two L.L.C.      Delaware    Smith Property Holdings Ballston    Place L.L.C.      Delaware    Smith Property Holdings Buchanan    House L.L.C.      Delaware    Smith Property Holdings Columbia    Road L.P.      Delaware    Smith Property Holdings Consulate    L.L.C.      Delaware    Smith Property Holdings    Cronin’s Landing L.P.      Delaware    Smith Property Holdings Crystal    Houses L.L.C.      Delaware    Smith Property Holdings Crystal    Plaza L.L.C.      Delaware    Smith Property Holdings Crystal    Towers L.P.      Delaware    Smith Property Holdings Five    (D.C.) L.P.      Delaware    

 
   **Subsidiary Name** **Organization** Smith Property Holdings Five    L.P.      Delaware    Smith Property Holdings Four    L.P.      Delaware    Smith Property Holdings Illinois    Center L.L.C.      Delaware    Smith Property Holdings Kenmore    L.P.      Delaware    Smith Property Holdings Lincoln    Towers L.L.C.      Delaware    Smith Property Holdings McClurg    Court L.L.C.      Delaware    Smith Property Holdings New River    Village L.L.C.      Delaware    Smith Property Holdings One (D.C.)    L.P.      Delaware    Smith Property Holdings One East    Delaware L.L.C.      Delaware    Smith Property Holdings One    L.P.      Delaware    Smith Property Holdings Parc Vista    L.L.C.      Delaware    Smith Property Holdings Reston    Landing L.L.C.      Delaware    Smith Property Holdings Sagamore    Towers L.L.C.      Delaware    Smith Property Holdings Seven    L.P.      Delaware    Smith Property Holdings Six    L.P.      Delaware    Smith Property Holdings Six (D.C.)    L.P.      Delaware    Smith Property Holdings    Springfield L.L.C.      Delaware    Smith Property Holdings Superior    Place L.L.C.      Delaware    Smith Property Holdings Three    (D.C.) L.P.      Delaware    Smith Property Holdings Three    L.P.      Delaware    Smith Property Holdings Two (D.C.)    L.P.      Delaware    Smith Property Holdings Two    L.P.      Delaware    Smith Property Holdings Van Ness    L.P.      Delaware    Smith Property Holdings Water Park    Towers L.L.C.      Delaware    Smith Property Holdings Wilson    L.L.C.      Delaware    Smith Realty Company     Delaware    SPH Springfield Station    L.L.C.      Delaware    Texas GP Properties LLC     Delaware    TRG-Pembroke Road, LLC     Florida    Turtle Run at Coral Springs    L.L.C.      Delaware    Warner Pointe, LLC     Delaware    Westminster Estates, L.L.C.      Texas