rè hé
refers to the Qing imperial resort at Chengde
Rehe, Qing dynasty province abolished in 1955 and divided among Hebei, Liaoning and Inner Mongolia; see also 避暑山莊|避暑山庄[bi4 shu3 shan1 zhuang1] (history)
热
rè
to warm up
河
hé
river (CL:條|条[tiao2],道[dao4])