Erenhot Saiwusu International Airport
The airport is 27km south of the city. There are regular flights to/from Bĕijīng (¥430) and Hunnu Air has offered flights between Èrlián and Ulaanbaatar, but schedules tend to be seasonal.
Getting same-day train tickets out of Èrlián is darn near impossible for Bĕijīng, so most people opt for the bus. The long-distance bus station is halfway between the consulate and the train station. From Èrlián there are buses to Bĕijīng, Hohhot and Dàtóng.
In Bĕijīng, buses depart/arrive at the Mùxīyuán bus station (木樨园汽车站; Mùxīyuán Qìchēzhàn). All buses to Èrlián leave around 4-5pm so turn up by 3pm for a ticket. To reach Mùxīyuán bus station by subway take line five to Liujiayuan station, take Exit D, and walk straight for 1km. Just before the road goes under Mùxīyuán bridge bear left and then left again down Dahongmen Lu (大红门路), the bus station will be on your right after 500m. A taxi to/from the Drum Tower should cost around Y40, make sure to use genuine blue-and-yellow painted cabs that have a meter, and avoid the dodgy black cabs that won't use a meter.