Throughout its span of history, 800 AD through 1400 AD, the Khmer Empire extended over most of what is now Thailand, Cambodia and parts of Vietnam. An imperial highway connected Phimai, the northernmost temple, to the royal capital at Angkor, a distance of 140 miles. Over 20 Khmer temples were built in Thailand. Many of these are just ruins now, but a number are still in sufficiently good state to show the unique designs, hard labor and religous ferver that existed then. The following are four of the most significant of these remaining temples.