Across the road from The Golden Mount is Wat Ratchanatdaram. It is a Buddhist temple which dates back to the mid-19th C. Here there are two things to have a look at; a small market selling Buddhist prapim (charms and amulets) and Loha Prasat.
Being not the most wise person about which Buddhist prapim to buy, a quick look was sufficient, so headed to the main attraction. Loha Prasat is a castle like monastery, which you are able to walk to the top and see another great view of Bangkok. Bare in mind that the stairs spiral to the roof ( 6 floors) so did take a bit of courage (and grip on the banister) for myself to reach the top!
Like most wats and attractions in Bangkok it closes at 5pm, so make sure that you don’t leave it to last minute to do!