Wat Si Saket, across from
Haw Phra Kaew, is a small Buddhist temple built in 1818 that hasn't been destroyed by the Siamese. Walls surrounding the tmeple showcase 2000+ Buddha statues, small and large.
30 minutes here will likely be more than enough. Opens from
8 am to 4 pm, with a lunch break from noon to 1 pm.
