Antigua is a city in Guatemala.
North/West towards Chimaltenango/Xela
Walk north past the stadium (the same street, basically, as the bus station and the market), heading towards Jocotenango. After about 500m, you'll get to a nice speedbump. If that doesn't work, another kilometer or so down the road is Jocotenango where there are more speedbumps and more traffic heading towards Chimaltenango.
From 5km up the hill that goes up from Cerro de la Cruz to El Hato, @justgettingaround hitchhiked to San Mateo Milpas Altas (past hobbitenango) and down to Antigua at least two or three times a week for two months. Was also able to luck out on a ride to Flores/Tikal. Thumbing worked; no issues, took at most 5-15 minutes for a ride.