Travel Ruinas is just off the Plaza de Armas in Cusco, on the way to the Marriott Hotel. This is a real travel agency, not just one of those tourist traps that sells fake alpaca sweaters but will also book day trips from Cusco.
I used them to book a very satisfactory 3D/2N excursion to Puno and Lake Titicaca. I travel alone, and was a bit nervous about setting up that excursion. With Travel Ruinas it was simple and seamless. They took care of everything, from the initial pickup at my hotel in Cusco, through the bus trips, the hotel in Puno, and the boat excursion on the Lake. The hotel they booked for me (Hacienda Puno) was, by far, the nicest place I stayed in Peru. All the drivers were prompt. I felt very secure and was quite satisfied.
And, the cost of the whole thing was very comparable to doing all that set-up myself, and I would NOT have done as good a job.
Imabizzybee