At one point Cusco was the capital of the Incan Empire so it is rich in history and places to visit.
We spent 5 days In Cusco. First of all, take it slowly the first couple of days as you will feel the altitude when walking too fast. Cusco is 11,15 feet and 3,400 meters above sea level. Walking, exercising and breathing can be difficult at times. At least while your body gets used to it. Some of the places we recommend to visit are the ruins of the Sacsahuaman and The Statue of Christ for some great Cusco views.
Most of the city is very walkable. We did not see a need to rent a car. We did take a taxi a couple of times. Before hiring a taxi, make sure to check with locals (Hotel employees or Airbnb Host) to ensure you know how much you should pay. Also, all prices are negotiable. We hired a taxis to take us to a couple of places, wait for us and bring us back.
Other historical sites include: Plaza de Armas, Cusco Cathedral and Temple of the Sun.
Cusco also offers a lot of great local restaurants. If you are not a vegetarian make sure to try the Guinea Pig and Alpaca. Other traditional meals are Lomo Saltado, Aji de Gallina and Papas a la Puancaina (vegetarian friendly). We recommend trying some amazing Pisco at Museo del Pisco and for an authentic Peruvian meal go to La Cusqueñita. We walked to most places (Except to the Statue of Christ).
Cusco is a very young city to party, drink and go out at night. It is also filled with restaurants, many of which target tourists. As you walk near the restaurants there are many restaurant employees on the sidewalks asking you to come in. We we say many, we mean way too many. As you can probably imagine, these places are usually more on the touristy side. On the places we recommended we did not see many tourists. We work hard on trying to avoid tourist traps where the food and drinks are not so good yet you pay very high prices. This is not to say that all touristy places are bad, we are implying that doing research can lead to better and more local experiences.