Just 30 miles from Orosi, the fascinating Guayabo National Monument is the most important archeological site in Costa Rica and the only major one uncovered in the country so far. Declared a national monument in 1973, the site comprises the remains of a pre-Columbian city dating back further than the 8^th century AD which was once home to over 20,000 people. Visitors to Guayabo can observe petroglyphs, residential mounds, and an impressive aqueduct system that is still functional today.

Birdwatching is also a popular activity at the site, which contains the last remaining pre-montane forest in the Cartago province. In this scenic area, toucans, brown jays, and oropendolas can all be observed along with mammals such as squirrels, armadillos, and coatis. Guided tours in Spanish ($20) are available and English speaking guides may be possible in the high season (between December and April).

Driving is the recommended method of reaching Guayabo, which is approximately eighty minutes by car from Orosi. The site is open from 8:00 a.m. to 3:30 p.m. seven days a week and admission costs just $5 USD.