🔄 Updated 21 Jun 2026
Phetchabun and Lopburi sit on the same road, Highway 21. The distance between the two town centers is roughly 250 kilometers, about three and a half hours of driving if you don't stop. But there's plenty along the way that people later wish they'd pulled over for — the ancient city of Si Thep, recently named a World Heritage site, and Lopburi's old town, where you can spend a full day among monuments from the reign of King Narai. This plan keeps the drive up about the nature of Khao Kho, then works its way back down through history, finishing in Lopburi just two hours short of Bangkok.
Read before you set off
This trip suits people with their own car, because the sights are spread out beyond the town centers and there's no convenient public transport linking them. If you take the BKS 999 intercity bus, it does run through Si Thep–Nong Phai–Lom Sak, but stopping off along the way on your own is tough.
The 3-day route at a glance
Starting from Bangkok or central Thailand, day one is a long drive up to Khao Kho in Phetchabun, with one night on the mountain. Day two is a full day around Khao Kho before easing south, stopping at Si Thep, then dropping down to sleep in Lopburi. Day three is walking Lopburi's old town in the morning, catching the sunflower fields or the Pa Sak dam mid-morning, then running into Bangkok in the afternoon. The whole trip comes to about 700 kilometers, but spread over three days it never feels like too much.
- Day 1 — Bangkok → Khao Kho (drive ~5–6 hrs), overnight on the mountain
- Day 2 — Around Khao Kho → down to Si Thep → overnight in Lopburi
- Day 3 — Lopburi old town → Pa Sak dam / sunflower fields → back to Bangkok
Book the activities in your Phetchabun trip ahead
Booking online ahead on Klook or GetYourGuide is usually cheaper than the gate and skips the queue. Pick only the experiences you actually want — prices and availability are shown live on each site.
The plan in detail
Up to Khao Kho
Khao Kho in the morning, then down to Si Thep
Lopburi old town, then back to Bangkok
What's worth stopping for along the way
If you've got time to spare or want to slow the trip down, Highway 21 has several more stops that don't take you far off the route. Slot them in whenever the pace feels right.
Si Thep Ancient City
Thailand's newest cultural World Heritage site, a Dvaravati city over a thousand years old. Khao Khlang Nok is the highlight — worth the walk up to see it.
Lopburi sunflower fields
Lopburi's winter landmark, whole fields of yellow blooms with mountains behind. Come in the morning when the flowers face the sun and look their best.
Pa Sak Jolasid Dam
The longest earthen dam in Thailand, with a tram running along the crest over wide reservoir views — a good place to stretch your legs before heading home.
Prang Khaek, Lopburi
The oldest Khmer tower in Lopburi town, sitting on a traffic island. A quick photo stop while you walk the old town.
Tips for driving Highway 21
- Fuel up when you pass a bigger town — between Chai Badan and Si Thep stations start thinning out, so don't let the tank drop below half
- The climb up Khao Kho is steep and winding — use a low gear to help brake, and avoid driving down the mountain at night if you're not used to it
- Leave extra time on Sunday evenings — the run back into Bangkok gets busy around Saraburi, so leaving Lopburi before 3 pm flows better
- Watch the monkeys in Lopburi — especially around Prang Sam Yot; don't leave food or bags anywhere a monkey can reach
You can trim it shorter
If you only have 2 days, drop Khao Kho: drive straight to Si Thep on the morning of day one, spend a night in Lopburi, then walk the old town on day two before heading back. You'll get a tight history trip that still covers the World Heritage site in full.
Want a full Phetchabun plan before adding Lopburi? See our guide to the whole province.
See the Phetchabun travel guide →