Adorned with or having a fountain; flowing or spouting like a fountain.
From fountain + -ed suffix indicating possession of a feature or quality. Fountain comes from Latin fontana (spring or water source).
Adjectives ending in -ed can be tricky because they can mean 'having' something (a blue-eyed cat) or 'treated with' something, but 'fountained' definitely means a place beautiful enough to deserve ornamental fountains.
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