The Palace of Versailles was home to French monarchy for about 100 years until the Revolution of 1789 changed all that. The over the top opulence last occupied by the Sun King Louis XIV is now available to the public as a museum including its surrounding gardens and manicured lawns. About a 35 minute train ride from the centre of Paris, this is one of the most popular day trips from the City of Lights.
Versailles is very busy all of the time. Since most other museums are closed on Tuesdays in Paris that is the busiest day, followed of course by weekends. There are two ways to get there; taking a tour which can be booked through a number of tourist sites at varying prices, or going on your own. The C train runs out to Versailles on a regular basis. From your neighbourhood metro stop head to the nearest RER station to get the train. Just follow the signs to be sure you are on the right one. If you choose to travel on a Sunday be warned that some of the regular commuter routes are cancelled or shortened and you may have to walk from one metro stop to another to get back on track. You can buy the ticket for the train at the metro stop and the subway portion is included in the fee of €14.60 return for two travelers.
Once there you just turn right out the train station, then turn left about two blocks later, following the crowd. It is about a 10 minute walk 
from the station to the Palace grounds. With the return train ride and time to explore this tour can be completed in a half day leaving you plenty of time to see more of Paris.
We would strongly recommend that you buy your tickets in advance. Go to http://en.chateauversailles.fr/plan-your-visit/tickets-and-prices to find the package that best suits your needs. Choose various options from Palace only entry at €18 per person up to a full package that includes the gardens, water fountain show and equestrian shows for €40. Tickets can be printed at home and brought with you. The site recommends that you buy the timed entry ticket which will get you into the shortest line. If you are planning to purchase the Paris Museum Pass Versailles is included with that.
The entry to Versailles itself seemed confusing to us. Everyone was funnelled through the same door and security checkpoint but there were three lines, none of which were clearly marked. The first, shortest and fastest was the timed or priority entry. The second was for folks who had purchased their entry tickets in advance but did not get a time, and the third was the ticket purchase line. If you start in the wrong line and have to go back to the end it will increase your wait time and frustration levels considerably.
Once inside plan at least 1.5 to 2 hours for a proper tour. The palace is huge but does not have as many stairs as the Louvre so much easier to navigate. Be sure to visit the State Apartments, and take the time to browse the amazing art work. There is an entire room of paintings by Peter Paul Rubens that were commissioned by Marie de Medici, and if you missed the Coronation of Napoleon at the Louvre it is recreated here. Most importantly marvel at the Hall of Mirrors.
The Palace of Versailles, opulence at its best, and the palace that all others in Europe are modelled after. It truly deserves the description of breathtaking.