Fabrica Coffee Roasters near our apartment, then walked to a bus stop at Praco do Comercio, where we boarded and headed to Belem. I had been really excited about visiting the Jerónimos Monastery but was worried the kids would be bored with it. Luckily they were amazing, happy to run on a spot of grass or find a bench to chill with activity books for a bit.
This is a super useful tip for visiting the Monastery with kids: there was a huge long line 100+ people deep to get in. We walked past the line, toward the next door to the left, which is for the archaeology museum, where the line for tickets was about 5 people deep, and where you can...buy tickets for the Monastery! Three minutes later we waltzed past the huge long line and right into the Monastery. Boom!
After lunch, we let the kids run around in the park, where they enjoyed trying the outdoor exercise equipment, playing on the playground, and exploring the unexpected Thai Pavillion.
After lunch, our three-year-old dozed in the toddler carrier while we explored the Maritime Museum. Our six-year-old tour guide had us running through the museum in record time while he paused only long enough at each big model ship to peek in and exclaim "Wow. WOW!" before dashing on to the next one.