| Bacau Observatory | Rumania | Bacău | — |
 Badalona Boreal observatory | España | Badalona | — |
| Badalona observatory | España | Badalona | — |
| Badalozhnyj observatory | Rusia | Krasnoyarsk Krai | — |
 Badlands Observatory | Estados Unidos | Quinn | — |
| Bagdad observatory | Estados Unidos | Bagdad | — |
| Bagnall Beach Observatory | Australia | New South Wales | — |
 Baikal Astrophysical Observatory | Rusia | Listvianka | 645 m |
| Baja Astronomical Observatory | Hungría | Baja | — |
| Baker Lake Magnetic Observatory | Canadá | Nunavut | — |
| Baker Observatory | Estados Unidos | Misuri | — |
| Bakersfield observatory | Estados Unidos | Bakersfield | — |
 Baksan Neutrino Observatory | Rusia | — | — |
| Baksan Underground Scintillation Telescope | — | — | — |
| Balbriggan Observatory | Irlanda | Balbriggan | — |
 Baldone Observatory | Letonia | Baldone Parish | 80 m |
| Ball State University Observatory | Estados Unidos | Indiana | — |
| Balzaretto Observatory | Italia | Roma | — |
| Bamberg observatory | Alemania | Bamberg | — |
| Bangui Magnetic Observatory | República Centroafricana | — | — |
| Banyoles observatory | España | Bañolas | — |
| Bar J Observatory | Estados Unidos | Lake Ashby | — |
| Barao Geraldo observatory | Brasil | Barão Geraldo | — |
 Bardsey Bird and Field Observatory | Reino Unido | Aberdaron | — |
| Bareket observatory | Israel | Modi'in-Maccabim-Re'ut | — |
| Barfold observatory | Australia | Glenhope | — |
| Barlad Observatory | Rumania | Bârlad | — |
 Barnard Observatory | Estados Unidos | Oxford | — |
| Barred Owl Observatory | Canadá | Ottawa Kanata | — |
| Barren Grounds Bird Observatory | Australia | — | — |
| Barrow Magnetic Observatory | Estados Unidos | — | — |
| Barton observatory | Australia | Canberra | — |
| BAS observatory | Italia | Scandicci | — |
 Base Amundsen-Scott | — | Región del Tratado Antártico | 2.835 m |
 Basic Environmental Observatory - Musala | Bulgaria | — | 2.925 m |
 Bassano Bresciano observatory | Italia | Bassano Bresciano | 58 m |
| Bastia observatory | Italia | Ravena | — |
| Bastidan observatory | Francia | La Bastide-des-Jourdans | — |
 Batabat Astrophysical Observatory | Azerbaiyán | Zangezur Mountains | 2.100 m |
| Battle Point Observatory | Estados Unidos | Bainbridge Island | — |
| Baugy observatory | Francia | Baugy | — |
 Bavarian Public Observatory Munich | Alemania | Giesing | 539 m |
| Baxter Garden Observatory | Reino Unido | Salisbury | — |
| Bayerwald observatory | Alemania | Neuhütte | — |
| Bayerwald observatory | Alemania | Spiegelau | — |
 Bayfordbury Observatory | Reino Unido | Bayford | — |
| BDI observatory | Australia | Bangor | — |
| Beaconsfield Observatory | Reino Unido | Penn | — |
| Beato Ermanno Observatory | Italia | Impruneta | — |
| Beersel Hills Observatory | Bélgica | Beersel | — |
| Behagi | — | Guipúzcoa | — |
| Behlen Observatory | Estados Unidos | Nebraska | — |
 Beijing Ancient Observatory | República Popular China | Jianguomen Subdistrict | — |
| Beijing Astronomical Observatory | República Popular China | Pekín | 960 m |
| Beijing Ming Tombs Magnetic Observatory | República Popular China | — | — |
| Beilen observatory | Países Bajos | Beelen | — |
| Beimian Tianwentai observatory | República Popular China | Ngari | — |
| Beine-Nauroy Observatory | Francia | Beine-Nauroy | — |
| Belesta observatory | Francia | Bélesta | — |
| Bellavista observatory | Italia | L'Aquila | — |
| Bellino observatory | Italia | Bellino | — |
 Belogradchik Observatory | Bulgaria | Belogradchik | — |
| Belsk Magnetic Observatory | Polonia | — | — |
| Bendestorf observatory | Alemania | Bendestorf | — |
| Beppe Forti Astronomical Observatory | Italia | San Giovanni Evangelista | — |
 BeppoSAX | — | — | — |
| Bergen-Enkheim Observatory | Alemania | Fráncfort del Meno | — |
| Berkeley Heights observatory | Estados Unidos | Berkeley Heights | — |
| Berlin-Babelsberg observatory | Alemania | Berlín | — |
| Bernezzo observatory | Italia | Cuneo | — |
 Bernoulliborg | Países Bajos | Groninga | — |
| Berri observatory | Australia | Ciudad de Monash | — |
| Berta observatory | España | Sabadell | — |
| Berthelot Observatory | Rumania | General Berthelot | — |
| Besely Observatory | Madagascar | Besely | — |
| Beta Orionis observatory | Argentina | Rosario | — |
| Betera observatory | España | provincia de Valencia | — |
 Beverly-Begg Observatory | Nueva Zelanda | Dunedin City | — |
 BGSU Observatory | Estados Unidos | Bowling Green | — |
| BiAnto Observatory | Italia | Melara | — |
| Bibai observatory | Japón | Bibai | — |
 Biblioteca Pública de Airdrie | Reino Unido | North Lanarkshire | 125 m |
 Bidston Observatory | Reino Unido | Wirral | — |
 Big Bear Solar Observatory | Estados Unidos | California | 2.060 m |
| Big Cypress Observatory | Estados Unidos | Fort Lauderdale | — |
| Big Water observatory | Estados Unidos | Big Water | — |
| Bigmuskie observatory | Italia | Mombercelli | — |
| Bilbao Observatory | España | Bilbao | — |
 Binnhill Tower | Reino Unido | Perth and Kinross | — |
| Biosphere 2 Observatory | Estados Unidos | Arizona | — |
| Birch Forest Observatory | República Popular China | Huairou | — |
| Bird Conservancy of the Rockies | Estados Unidos | — | — |
| Bird Migration Research Station | — | — | — |
| Birkdale observatory | Australia | Birkdale | — |
| Bishopstoke observatory | Reino Unido | Bishopstoke | — |
 Bismarck Tower (Remscheid) | Alemania | Remscheid | 340 m |
| Bixhoma observatory | Estados Unidos | Bixby | — |
| BKH Observatory | Estados Unidos | Fearrington Village | — |
 Black Birch Astrometric Observatory | Nueva Zelanda | Marlborough District | 1.366 m |
| Black Birch Station | Nueva Zelanda | Marlborough District | — |
| Black Forest Magnetic Observatory | Alemania | Rottweil | — |
| Black Forest Observatory | Estados Unidos | Colorado | — |
| Black Moshannon Observatory | Estados Unidos | Pensilvania | — |
| Black Mountain Observatory | Estados Unidos | Los Altos Hills | — |
| Black Swamp Bird Observatory | Estados Unidos | Oak Harbor | — |
| Blackberry Observatory | Estados Unidos | Port Allen | — |
| BlackBird observatory | Estados Unidos | Weed Lookout Tower | — |
| BlackCAT | Estados Unidos | — | — |
 Blackrock Castle Observatory | Irlanda | Cork | — |
| Blanes observatory | España | Blanes | — |
| Blanquita observatory | España | Rivas-Vaciamadrid | — |
 BLAST | — | — | — |
| Blatec Field Station | República Checa | Región de Bohemia Meridional | — |
| Blauvac observatory | Francia | Blauvac | — |
 Bleien Radio Observatory | Suiza | Gränichen | 469 m |
| Blue Canyon observatory | Estados Unidos | Blue Canyon | — |
| Blue Mesa Observatory | Estados Unidos | New Mexico | — |
| Blue Mountains Observatory | Australia | Leura | — |
| Blåvand Fuglestation | Dinamarca | Varde | — |
| Boambee observatory | Australia | Boambee | — |
 Bobergs observatorium | Suecia | municipio de Estocolmo | — |
| Bobergs observatory, Skansen | Suecia | municipio de Estocolmo | — |
| Boca Raton Observatory | Estados Unidos | Boca Raton | — |
| Bocholt observatory | Alemania | Bocholt | — |
| Bochum Observatory | Alemania | — | — |
 Bohnenberger Observatorium | Alemania | Calw | — |
 Boleslav Tecla Observatory in Moravská Třebová | República Checa | Moravská Třebová | 412 m |
| Bollwiller observatory | Francia | Bollwiller | — |
| Bologna Observatory | Italia | Bolonia | — |
| Boltwood Observatory | Canadá | Stittsville | — |
| Bolzaneto observatory | Italia | Bolzaneto | — |
 BOOMERanG experiment | — | — | — |
| Bootes Observatory | España | Boecillo | — |
| BOOTES-2 Observatory | España | Algarrobo | — |
 Bordeaux Observatory | Francia | Floirac | — |
| Borken observatory | Alemania | Borken, North Rhine | — |
| Bornheim observatory | Alemania | Bornheim | — |
| Borok Magnetic Observatory | Rusia | — | — |
| Borowiec Astrogeodynamic Observatory | Polonia | Borówiec | — |
 Bosianu Astronomical Observatory | Rumania | Bucarest | — |
 Boswell Observatory | Estados Unidos | Nebraska | — |
| BOSZA Observatory | Hungría | Distrito de Pécs | — |
 Bothkamp Observatory | Alemania | Schleswig-Holstein | — |
| Boulder Geomagnetic Observatory | Estados Unidos | Boulder | — |
| Boulder Knolls observatory | Estados Unidos | Hidden Meadows | — |
| Boulder Magnetic Observatory | Estados Unidos | — | — |
 Bowman Observatory | Estados Unidos | Connecticut | — |
| Boyeros Observatory | Cuba | La Habana | — |
 Brackett Observatory | Estados Unidos | Claremont | — |
| Bradbury observatory | Reino Unido | Stockton-on-Tees | — |
| Bradley Observatory | Estados Unidos | Georgia | — |
| Bradstreet Observatory | Estados Unidos | Pensilvania | — |
| Braeside Observatory | Estados Unidos | Flagstaff | 2.152 m |
| Brandon Magnetic Observatory | Canadá | — | 380 m |
| Bray-et-Lû observatory | Francia | Bray-et-Lû | — |
 Brazil National Observatory | Brasil | Vasco da Gama | — |
| Bredenkamp Observatory | Alemania | Bremen | — |
| Breitenweg observatory | Alemania | Bergisch Gladbach | — |
| Brelingen observatory | Alemania | Wedemark | — |
| Bremen observatory | Alemania | Bremen | — |
| Brescia observatory | Italia | Brescia | — |
 Breslau observatory | Polonia | Breslavia | — |
| Brignoles observatory | Francia | Brignoles | — |
| Brisbane Observatory | Reino Unido | North Ayrshire | — |
| BRITE-Austria | — | — | — |
 BRITE-Heweliusz | — | — | — |
 BRITE-Lem | Polonia | — | — |
| BRITE-Montréal | — | — | — |
| BRITE-Toronto | — | — | — |
| Brixiis Astronomical Observatory | Bélgica | Kruibeke | — |
 Brno Observatory and Planetarium | República Checa | Brno-střed | 305 m |
| Brooklyn Park observatory | Australia | Brooklyn Park | — |
| Brooks Astronomical Observatory | Estados Unidos | Míchigan | — |
| Brooks Observatory | Estados Unidos | Ohio | — |
| Broome Bird Observatory | Australia | Western Australia | — |
| Brorfelde Magnetic Observatory | Dinamarca | Holbæk | — |
| Brownstown Observatory | Irlanda | Condado de Meath | — |
 BRRISON | Estados Unidos | — | — |
| Brukkaros Solar Observatory | Namibia | — | — |
| Bruno Zugna Observatory | Italia | Trieste | — |
 Bruno-H.-Bürgel-Sternwarte | Alemania | Berlín | 83 m |
| Brusque observatory | Brasil | — | — |
| Brynllefrith Observatory | Gales | Pontypridd | — |
| BSA observatory | Italia | Aeropuerto Internacional de Cuneo | — |
| BSCR Observatory | Italia | Santa Maria a Monte | — |
| BSH Byulsem Observatory | Corea del Sur | Busan | — |
| Bucharest Astronomical Observatory | Rumania | Bucarest | 86 m |
| Bucknell Observatory | Estados Unidos | Pensilvania | — |
| Budkov Magnetic Observatory | República Checa | Budkov | — |
 Buehler Planetarium and Observatory | Estados Unidos | Davie | — |
| Buenaventura Suarez observatory | Argentina | La Punta | — |
 Building 20 | Canadá | La Cité-Limoilou | — |
 Bukit Jugra lighthouse | Malasia | Kuala Langat | — |
 Bukit Melawati | Malasia | Selangor | — |
| Burgsolms Observatory | Alemania | Wetzlar | — |
| Burjassot Observatory | España | Burjasot | — |
| Burke-Gaffney Observatory | Canadá | Halifax | — |
| Burleith Observatory | Estados Unidos | Washington D. C. | — |
| Burlington observatory | Estados Unidos | Nueva Jersey | — |
| Burlington remote site Observatory | Estados Unidos | Nueva Jersey | — |
| Burnt Tree Hill Observatory | Estados Unidos | Bristol | — |
 Burrell Memorial Observatory | Estados Unidos | Ohio | — |
| Burwash observatory | Reino Unido | Burwash | — |
| Busot observatory | España | Alicante | — |
 Bussloo public observatory | Países Bajos | Voorst | — |
 Buthiers Observatory | Francia | Buthiers | 87 m |
| Byrne observatory | Estados Unidos | Río Santa Ynez | — |
| Bükki Star | Hungría | Répáshuta | — |