You will land at the Ruzyne international airport (PRG).
To get to the hotel, you can use the Prague public transport system. It is very reasonably priced, runs reliably and covers the entire Prague very well. The bus line 119 will take you from the airport to the Dejvická station (the terminal station), which is located less than 90m from the entrance to the hotel. The public transport company has information stands (that also sell tickets) at both airport terminals.
You can also take a taxi but please be careful – Prague taxi drivers are infamous for charging exorbitant amounts, especially to foreigners, so agree on the price before you get on. A fair fare from the airport to the Diplomat Hotel should be well under 500 CZK (20 EUR).
International trains stop either at Praha Hlavní nádraží or Praha Holešovice stations. The metro system runs through both of these stations. You need to get to the Dejvická station of line A. Follow the signs to get to the correct exit; the hotel is just about 100m away.
Before you enter the metro area, you need to get your tickets. A ticket costs 32 CZK and is valid for 90 minutes; you may need an additional 16 CZK ticket if you carry a large piece of baggage. If you plan to do lots of sightseeing, consider getting a 24-hour or 3-day pass priced at 110 CZK or 310 CZK respectively – one large piece of baggage is included in the price. Details about trevel fees can be found here. Remember to validate the ticket(s) by stamping them in the yellow machine.
Use your favorite route planner site, navigation device, or the Google map below. The hotel's street address is Evropská 15. The hotel offers garage parking (for an extra charge).