ลพบุรี or ลบบุรี (Lopburi or Lobburi)(!
The place cannot possibly be pronounced Lobburi!
In the Thai language, if a consonant ends in "B" then it is pronouncd "P" (see Thai Phrasebook). In this case, the City first syllable actually does end in "P"(พ), and not "B"(บ)
Had it ended in "B" then Lobburi would be a very slim option, but since it does not, then it is definitely not an option.
I also have a friend who lives there who knows nothing about "Lobburi"
So I have reverted the "Lobburi".