The major sights of interest in Cajamarca are all around the Plaza de Armas or within easy walking distance of it. Except for the Inca Baths, you're unlikely to require transportation unless you're staying at one of the country hotels on the outskirts of town, which are serviced by taxi and, to a lesser extent, colectivo.
By Taxi -- Taxis are easy to come by in the center of Cajamarca. They circulate around the Plaza de Armas and the streets leading off it. Most in-town fares are about S/3. To call a cab, try Taxi Seguro (tel. 076/365-103) or Taxis Unidos (tel. 076/368-888).
By Organized Tour -- Reliable tour agencies include Inca Baths Tours, Jr. Amalia Puga 653 (tel. 076/362-938); Cumbe Mayo Tours, Jr. Amalia Puga 635 (tel. 076/822-938); and Cajamarca Travel, Jr. Dos de Mayo 570 (tel. 076/365-651). These companies offer city tours and inexpensive, pooled half- and full-day tours to sights in the countryside around Cajamarca (including Cumbe Mayo, Otuzco, Colpa, and Inca Baths). Most standard tours cost S/25 to S/35. Several agencies also offer long-distance tours to the famed but remote Kuélap ruins for around $600 per person. All agencies advertise English-speaking guides, but fluency is a relative term. The best bets are Inca Baths Tours and Cumbe Mayo Tours.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.