| 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 |