1. Pedra da Gavea is a massive rock formation located in Tijuca National Park, Rio de Janeiro, Brazil. It is one of the largest monoliths in the world, towering 842 meters above sea level. The name \"Gavea\" refers to the shape of the rock, which resembles the head of a Sphinx. The climb to the summit is challenging but rewarding, providing unparalleled views of the city and the Atlantic Ocean. The hike takes approximately 3-4 hours, depending on the route chosen and the fitness level of the hiker. It is recommended to climb with a trained guide and not to attempt the ascent in adverse weather conditions.

2. Pedra da Gavea does not have an official working time as it is located in a national park. However, the park is open daily from 8 am to 5 pm. The park’s phone number is +55 21 2492-2252.

3. Pedra da Gavea can be accessed by car or public transportation. The park entrance fee is R$20 (approximately USD 3.50) per person for the day. Visitors can take a taxi or Uber to the park entrance, or take bus 233 or 360 from the city center to the entrance. From there, it is recommended to hire a guide for the climb. The cost of a guide may vary depending on the season and demand, but it is usually around R$200 (approximately USD 35) for the climb.