1. Senate Square (Senatskaya Ploshchad) in St. Petersburg, Russia, is a historic public square located in the city center. It is home to several important landmarks, including the bronze equestrian statue of Emperor Alexander I, the iconic Senate and Synod Buildings, and the famous St. Isaac's Cathedral.

2. The square is open to the public at all times as it is an outdoor area. However, the opening hours of the buildings surrounding the square may vary. It is best to visit during daylight hours for the best experience.

3. There is no entrance fee to visit Senate Square itself as it is a public space. However, if you wish to visit the museums or attractions nearby, such as St. Isaac's Cathedral, there may be an entrance fee. The square is easily accessible by public transportation, including buses, trams, and the metro. Visitors can also reach the square on foot from various points in the city center. For specific transportation information, it is recommended to check the official website of the attractions you plan to visit.