| 2025-05-10 | Deep defenses |
| 2024-12-07 | Siege deterrents |
| 2023-05-10 | They're found around castles |
| 2022-01-07 | Strategic bodies of water |
| 2021-08-19 | Castle defenses |
| 2018-05-13 | Deep defenses |
| 2018-01-01 | Rings of water around castles |
| 2012-03-14 | They're crossed by bridges |
| 2010-07-18 | Things that drawbridges bridge |
| 2010-07-09 | Tokyo Imperial Palace features |
| 2010-05-10 | Castle-defending ditches |
| 2004-01-30 | Siege deterrents |
| 2002-09-15 | Zoo dividers |
| 2002-04-16 | Castle protectors |
| 1999-03-14 | Obstacles for marauders |
| 1998-10-22 | Zoo barriers |
| 1998-10-18 | Deep ditches |
| 1998-03-02 | Castles' barriers |
| 1996-02-20 | Drawbridges cross them |
| 1994-10-30 | Protective rings |