Walk east down Gongti Beilu until you get to the 3rd Ring road, go down into the subway, this will be Line 10. Buy a ticket from the machine (2 RMB each), go north (toward "Bagou"), get off at Beitucheng station. Maps in the stations and the trains are in Chinese and English, as are announcements. If Line 8 is open, transfer at Beitucheng station and it will take you to the Olympic Green. If it is not open, exit the subway and walk north (about 20 minutes) until you reach the south end of the Green. I haven't been there in awhile, but I thought it was open for wandering around. Getting into a peek of the individual buildings requires purchase of a ticket I believe. You can also taxi there, tell taxi driver "Bei sihuan, niao chao." Your hotel should be able to write this down in Chinese for you. Taxi from hotel to there should be about RMB 30.