While some of Peru’s adobe ruins require a little imagination to understand, no such effort is required for Sechín (5 km southeast of Casma, 8 a.m.–5 p.m. daily, US$1.50), a temple complex built around 1500 B.C.
Along the temple’s base, hundreds of warriors with their mutilated prisoners are carved into the granite with startling and gruesome detail. Soldiers carved into stone columns march on both sides toward the temple entrance with decapitated heads of the defeated hanging from their bodies. The range of human cruelty exhibited at Sechín is a prelude to the rituals of human sacrifice during the Moche and Chimú empires.
The adjacent Museo Max Uhle contains reconstructed murals along with models of Sechín and other nearby ruins. Bilingual guides are available for the museum and the temple for US$4.
To arrange a guide in advance, contact Miguel Chiri Valle (tel. 01/423-2515, www.angelfire.com/mi2/tebac ). Miguel, a fluent English speaker, will arrange transportation and accommodation to and from Lima  or another northern city.
For archaeology buffs, Sechín is only one of several sites in the Casma area that can be visited in a daylong circuit. Nearby lies Sechín Alto, a deteriorated U-shaped complex. Farther south at Km 361 of the Panamericana, but only accessible with four-wheel drive, is the fortress of Chanquillo, a watchtower surrounded by three concentric walls.
All the major bus companies stop at Casma, which is a five- or six-hour drive from Lima . Recommended companies include Cruz del Sur, Ormeño, and Flores, which head to Trujillo  and beyond. Casma, along with Chimbote farther north, is also the starting point for the dramatic, though bumpy, Casma Route  over the 2,800-meter Callán Pass to Huaraz , which offers excellent views of snow-covered mountains.
Taxis charge US$5 for the 15-minute drive north to Tortugas. The cheaper, three-wheeled canopied motorcycles are not recommended for the exposed highway drive.