North of Yaxhá [1] on a road suitable only for dry-season driving is the Late Classic site of Nakum, now being excavated. Near the site lies the marshy swampland of Bajo La Justa, which was under intense cultivation during Mayan times. You’ll pass through it on your way there.
Nakum features the usual assortment of pyramids, plazas, and temples, though there are some unique arches found here along with stelae dating from A.D. 771–849. Noted archaeologist Alfred Tozzer passed though here in 1909–1910, working for the Peabody Museum; he recorded his findings in a work titled, A Preliminary Study of the Prehistoric Ruins of Nakum, Guatemala.
Links:
[1] http://www.moon.com/destinations/guatemala/peten/the-maya-biosphere-reserve/yaxha-nakum-naranjo-natural-monument/yaxha