About halfway up the hill, a side path leads off the staircase to the Kantaka Cetiya — a partly ruined brick stupa from the 2nd or 1st century BC, one of the oldest at the site. The dome itself is much eroded, but the four projecting vahalkadas — sculpted frontispieces at the cardinal points — are unusually well preserved. Each is carved with bands of dwarves, elephants, geese, and ornament: some of the earliest figurative sculpture in Sri Lanka.
Easy to miss in the rush to the summit; the carvings reward a slow look.