2 sentences

1. 礼堂内气氛庄严肃穆。

   lǐ​táng nèi qì​fēn zhuāng​yán sù mù.

   The atmosphere in the auditorium was solemn and grave.

   Source: Dong Chinese Dictionary

2. 纪念馆内的气氛庄严肃穆。

   jì​niàn​guǎn nèi de qì​fēn zhuāng​yán sù mù.

   The atmosphere inside the memorial hall was solemn and respectful.

   Source: Dong Chinese Dictionary