Unless talking to foreigners who don't know any different, Thais will never call their capital city Bangkok – indeed, some Thais in the more remote provinces may never have even heard of it being called that. Instead in Thai it is known as Krung Thep, which roughly translates to 'City of Angels'. Bangkok (translating as 'village of wild plums') was the original site for the capital city and was located west of the Chao Phraya river (in modern day Thonburi).

In 1782, King Rama I decided to move to a more defensible site and moved across the river to found his new capital, Krung Thep. For whatever reason, foreigners have never since caught up with the name change and the old name of Bangkok has stuck. In recent years, Krung Thep/Bangkok has expanded at such a fast rate that it now sprawls over a huge mass of land on both the sides of the Chao Phraya and has engulfed the once independent Thonburi.

In the official English romanisation, this is certified as the longest place name in the world in the Guinness book of records. It's pronounced something like:

Krung Thep Mahanakhon Amon Rattanakosin Mahinthara Ayuthaya Mahadilok Phop Noppharat Ratchathani Burirom Udomratchaniwet Mahasathan Amon Piman Awatan Sathit Sakkathattiya Witsanukam Prasit

According to into-asia