The Central Highlands is the region around Guatemala City, stretching northwards to the Northern Lowlands in Guatemala.
The countryside around Antigua and Guatemala City is a spectacular landscape of volcanoes, forests of pines, meadows, corn fields and coffee plantations with occasional villages. It is well worth a visit. Looming over the capital is the Pacaya volcano which is one of the most active volcanoes throughout Central and South Americas.
The lush mountainous region of Alta Verapaz has an annual average temperature of 21 degrees Celsius with a rain fall of 178cm. Alta Verapaz is home to the Pokemchi and Kekchi mayan people groups. The capital of this area is Coban.
If you are arriving by air, you will be coming in from Aurora International Airport. To move on from the airport, you can either take scheduled shuttle buses to Antigua or taxis from outside of the terminal.
Guate City buses cost Q1 as of early 2007 and they offer a good way of getting around if you aren't heading through outlying slums.
Since Guatemala's governmental system is centralized in Guatemala City, many national and international non-governamental organizations are based on the capital city as well. There are numerous foreign NGOs in Antigua also since Antigua is a hub of foreign volunteers. See those articles for information on volunteer opportunities.
Given the opportunity, most Guatemalans would opt for something besides the usual corn and beans with some occasional meat of some sort. Don't expect great cuisine there, but the food can be quite good.
Guatemala City has rather alarming rate of crime in some areas. Stay out of trouble by using plenty of common sense. In Zone 1, after dark, walk directly to places you want to go and know where you are going. In the Zona Viva (Zone 10), follow normal precautions anytime, including after dark. Don't get drunk in any of the nightclubs and then stagger back to your hotel. That could attract a would-be robber there.