San José will most likely be your starting point in Costa Rica, centrally located in the highlands, with an international airport and good connections to every part of the country. I only spent one night here, but that was enough to get a first impression of city life, the colonial architecture and the lively markets.
Some neighborhoods in San José call for caution, pay attention to a safe location when choosing accommodation.
My flight was with Air Europa from Frankfurt via Madrid and Panama City to San José, including all stopovers I was traveling for around 18 hours, there are no direct flights from Germany. At Juan Santamaría airport, the cheap Black & White Tuasa buses will take you into the center, or alternatively an Uber or taxi.
I stayed at Selina Hostel, only a 10–15 minute walk from the center in a safe area. For about €70 a night I got friendly staff, a modern, stylish ambiance and a good feeling about the location, for San José I'd book it again anytime.
At San José's biggest market (Mon–Sat, 6am–6pm), the best move is to try specialties like fried plantain, avocado, and beans with rice, cheap, authentic and right in the middle of the colorful market bustle.
A modern street food market (daily 12pm–10pm) as an alternative to the Mercado Central, with cocktails, beer, sangria and a big selection of dishes.
A guided tour through the National Theatre (about $10, daily 9am–5pm) is worth it for the elaborate ceiling paintings and chandeliers.
At the Jade Museum (about $16, daily 8am–5pm) on Avenida Central, you get a fascinating look into Costa Rica's pre-Columbian history.
For the rest of your time, a stroll through the center around Plaza de la Cultura is plenty.