Saint Nicholas Cathedral, located in the heart of Monaco, is a magnificent Roman-Byzantine style cathedral that holds great historical and cultural significance. Here is some information about this iconic landmark:

History:
The construction of Saint Nicholas Cathedral began in 1875 and was completed in 1903. It was built on the site of a 13th-century church dedicated to Saint Nicholas, the patron saint of sailors. The cathedral was designed by Charles Lenormand and incorporates white stones from nearby La Turbie, giving it a stunning appearance.

Features:
The cathedral's exterior is adorned with beautiful domes and arches, while the interior boasts impressive frescoes, stained glass windows, and intricate mosaics. The main altar is made of white Carrara marble and features a statue of the Virgin Mary. The cathedral also houses the tombs of many members of Monaco's ruling Grimaldi family, including Prince Rainier III and Princess Grace.

Tips for Visitors:
1. Dress Code: As a place of worship, it is important to dress modestly when visiting the cathedral. Avoid wearing shorts, sleeveless tops, or revealing clothing.

2. Photography: Photography is not allowed inside the cathedral, as it is considered a place of reverence. However, you can capture the beautiful exterior and the stunning views of Monaco from the cathedral's surroundings.

3. Opening Hours: The cathedral is open for visitors from 8:30 am to 7:00 pm on weekdays, and from 8:30 am to 6:00 pm on weekends. However, it is closed during religious services, so it is advisable to check the schedule in advance.

4. Masses and Religious Services: The cathedral holds regular religious services, and attending one can be a unique and spiritual experience. Check the schedule in advance if you would like to participate.

5. Nearby Attractions: While visiting the cathedral, take the opportunity to explore the surrounding area. The Prince's Palace, Oceanographic Museum, and Monaco-Ville are all within walking distance and offer fascinating insights into Monaco's history and culture.

Saint Nicholas Cathedral is not only a religious site but also a symbol of Monaco's rich heritage. Its stunning architecture and historical significance make it a must-visit destination for tourists seeking a glimpse into the principality's past.