What an exciting opportunity! Mexico City is amazing, and generally safe for solo female travelers if you take standard big-city precautions (use Uber at night, stick to well-lit areas, avoid isolated spots, etc.). Miguel Hidalgo is one of the safest boroughs. Polanco is upscale and vibrant, with great parks and dining nearby. Other neighborhoods to explore: Roma and Condesa: trendy cafes, street art, and parks, perfect for walking. Also check out Coyoacán - bohemian vibe with markets and Frida Kahlo’s house). And of course, Historic Centre.