Nohoch Mul (Big Mound) is also known as the Great Pyramid, which sounds a lot better than Big Mound. It reaches a height of 42m, making it the second-tallest Maya structure on the Yucatán Peninsula. Calakmul's Estructura II, at 45m, is the tallest. Climbing the old steps can be scary for some. Two diving gods are carved over the doorway of the temple at the top (built in the post-Classic period, AD 1100–1450), similar to sculptures at Tulum.
The view from up top is over many square kilometers of flat scrubby forest, with peeks of lake. The trail to Grupo Nohoch Mul takes you past several interesting sights along the way. Northeast of the Grupo de las Pinturas turnoff you'll reach one of Cobá's two juego de pelota courts. Look at the ground in the center of the court to spot a carved stone skull (the winner or loser of the ball game?) and the carved relief of a jaguar.
After the ball court, the track bends between piles of stones – a ruined temple – and you reach a junction of sorts. Turn right (east) and head to the structure called Xaibé . This is a tidy, semicircular stepped building, almost fully restored. Its name means 'the Crossroads,' as it marks the juncture of four separate sacbés. Going north from here takes you past Templo 10 and Stela 20 . The exquisitely carved stela – worn, but not nearly so badly as the others – bears the date AD 730 and a familiar theme: a ruler standing imperiously over two captives. In front of it is a modern line drawing depicting the original details.