Some pretty serious clashes between anti-government protesters and riot police taking place right now in the vicinity of Ratchadamnoen Avenue. Khao San Road is still safe but tear gas is in the air as close as Rattanakosin Exhibition Hall. The whole of Ratchadamnoen is best avoided. Also a tense situation at the Ministry of Interior, not far from the Grand Palace. If you're in the Old City, you're best off sticking close to KSR and/or the river, or taking the express boat down to Chinatown and/or to Saphan Taksin to connect with the skytrain. Silom, Sukhumvit, Siam Square, Pratunam and Victory Monument all perfectly safe right now.