The glass-walled building in front is the rose garden. It's set up as a greenhouse, so you can admire the roses any time you like.

Literal

Front-[attributive-の] glass-walled [attributive-の] building [topic-は] rose-garden is-[explanatory-なんです]. Greenhouse [to-に] become-[continuous-ていて], always roses [object-を] can-admire-[potential]-[come-to-be-ようになってる][explanatory-んです][assertive-よ].

Tour-guide explanation style. 手前 ('in front, near at hand, this side') marks a spatial position from the speaker's point of view. ガラス張り ('glass-walled, glass-fronted') uses 張る 'to stretch, to cover' as a past attributive — a lexicalized compound. 薔薇 ('rose') is written with the full kanji (often in katakana バラ or hiragana due to complexity). ~ようになっている ('is set up so X is possible') for designed affordances.