Visitors are impressed by nature and geologic side of the area, but Thingvellir had been declared Unesco heritage due to its hitorical value. Thingvellir means "assembly fields": the first Icelandic national parliament was founded here in 930, you can find more info at https://en.wikipedia.org/wiki/Thingvellir.
Let's proceed with a brief description of the main path of the area: it starts next to the information center. There are many wooden footbridges, to avoid issues with underground erosion. Just a sight to Thingvallavatn lake, the biggest natural lake in Iceland and then let's walk inside the ravine! Is is so smooth and regular that cars were allowed to pass on it until 1967. The path turn right toward the lake Thingvallavatn, the church and the small graveyard. Now we can proceed to the rift, (very impressive!) until we get the Oxararfoss fall, a nice waterfall but not so impressive compared to other falls we'll see.

From now on, the path comes back following the rift. We point out some pahoehoe lava fields (typical sign of effusive activity on divergent earth plates) on our way back to the car park.