Number + 所 + Institution Noun
The classifier 所 (suǒ) is used to count institutions such as schools, hospitals, and research centers. When specifying a number of such institutions, 所 is placed between the number and the noun. For example, 一所学校 means 'one school.'
这座城市新建了两所医院。
Zhè zuò chéngshì xīn jiàn le liǎng suǒ yīyuàn.
This city has newly built two hospitals.
我们镇上只有一所小学。
Wǒmen zhèn shàng zhǐyǒu yī suǒ xiǎoxué.
There is only one elementary school in our town.
他在一所著名的研究所工作。
Tā zài yī suǒ zhùmíng de yánjiūsuǒ gōngzuò.
He works at a famous research institute.