1. St. Mark's Basilica, also known as Basilica di San Marco, is a stunning cathedral located in Venice, Italy. It is one of the most famous landmarks in the city and a prime example of Byzantine architecture. The basilica is dedicated to St. Mark the Evangelist, whose remains are housed in a sarcophagus inside.

The exterior of the basilica is adorned with intricate mosaics and marble columns, while the interior is decorated with gold mosaics, paintings, and beautiful sculptures. One of the highlights of the basilica is the Pala d'Oro, a golden altarpiece adorned with precious gems and jewels.

2. St. Mark's Basilica is open to visitors daily, usually from 9:30 am to 5:00 pm. The opening hours may vary, so it is recommended to check the official website or contact the basilica directly for updated information. Unfortunately, I do not have a phone number available at the moment.

3. Admission to St. Mark's Basilica is free, but there are additional charges to visit certain areas such as the Pala d'Oro, the Treasury, and the Museum. It is recommended to book tickets in advance, especially during peak tourist season, to avoid long queues.

To reach St. Mark's Basilica, you can take a vaporetto (water bus) to the San Marco stop or walk from various parts of Venice. The basilica is located in the famous St. Mark's Square, making it easily accessible from different parts of the city.