From the Okecie airport to guest rooms of the Warsaw Polytechnique.
We assume you will arrive by airplane. This means, you will come to the Okecie airport. From there you can take a bus, line 188. This first goes along the Zwirki i Wigury st., for about 6 kilometers. Then it turns right onto Wawelska St. Now, the bus approaches Riviera. The building is very characteristic, tall and in two shades of blue arranged into two large triangles. It is slightly to the right of the street. At some point the bus will go under Aleje Niepodleglosci, then it comes to the crossing with Warynskiego street. You should get off there, at a stop just before the crossing. Bus stops in Warsaw have their names. This one is "Metro Politechnika".
You will now be on Rondo Jazdy Polskiej (with a statue of two horsemen on a high column) you will see the Riviera dormitory at South-East. The dormitory is wedgeg between two streets: Warynskiego and Polna. Long time ago there was just a crossing of these two streets there. Now, both Polna and Warynskiego are cut by the Trasa Lazienkowska - the big one with a lot of fast going car. You sholud find your way to the opposite (North - West) side of the crossing of Polna and Warynskiego. Then you follow Polna Street to building number 50. You should use the side entrance.
You need to buy bus tickets in a kiosk at the airport. You will need one for you and one for your luggage (unless it is very small). You activate the ticket by inserting it into a slot of a yellow device in the bus.
You can also take a taxi instead of all that. This is altogether less than 10 kilometers and should cost maybe 40 zlotys (10 EUR). Just avoid the taxi drivers approaching you in the airport hall - they will charge you more than a taxi taken at the taxi stand right outside the exit.
From guest rooms of the Warsaw Polytechnique to the Banach Center (Sniadeckich 8).
You should go along the Polna street in the direction of increasing home numbers. After 50 meters or so you will come to the Plac Politechniki. Then you turn right, cross the Nowowiejska street and the next street is Sniadeckich. You turn right and now you walk along the Sniadeckich street. The Banach Center is at Sniadeckich street 8 (left side of the street). Altogether, it takes 3 minutes and 3o seconds (checked it today - P.T.)
Here is the picture of the building