Maker Faire Lisbon will take place at the beautiful Pavilhão do Conhecimento, located in the Parque das Nações in Lisbon, which enjoys a prime riverside location to the northeast of the city in a modern, airy district packed with interesting stuff to see.
The Pavilhão is located only a block (5 min walk) away from Oriente Station, which is a public transport hub you can get to via train, subway or bus.
Alameda dos Oceanos, Lote 2.10.01
Here's a map of the place.
There is no shortage of information as how to get there, but still, here are a few extra pointers: