The small fishing village of Chorrillos that has been engulfed by Peru's ever expanding capital as a new suburb is an excellent destination for those with time to spend in Lima.
It began as an Indian fishing village and later became a seaside resort for Lima's well to do more than a century ago. The city is quite large, however, almost all sites of interest line the Costa Verde or the first few blocks from the Malecón, or boardwalk. Chorrillos is just south of Barranco, a 5-minute cab ride.
The food here is one it's lasting legacy and the reason most will go there today. There are many good cevicherias here such as Sonia and La Casa de Luchita. The shacks surrounding the fish market on the shore is an excellent place to sample a variety of dishes and fish that are caught by the fleet of fishermen that crowd the docks every morning. The Chorrillana style of cooking, which is based in tomatoes and chillies was created here.
Playa Herradura is a great classic beach spot set in a small bay that is isolated from the rest of Lima's coast. There are a dozen or so restaurants that line the road there and little else. It is well known in Lima as one of the best places to surf.
Other aspects of the city worth visiting are the Club de Regattas and Iglesia San Pedro (which I once lived directly across from).
If you get lost in the chaos of Lima the city is simple to find. The colossal white cross that stands high on El Solar, the hill that corners the town, can be seen from as far away as Callao on a clear night.