See also the Maynooth University Location pages for information about travelling to Maynooth.
Trains to Maynooth depart from Connolly Station, some also from Pearse Station. The usual interval is about 20-40 minutes (check timetables at http://www.irishrail.ie, click on "Printed Timetables"); journey time about 40 minutes plus 15 minutes walking time to the Dept.
After leaving the station, cross the canal by a footbridge; in 5 mins turn left at the traffic lights to the old (South) campus gate; keep right after the gate, and in few more minutes cross to the North Campus by the pedestrian crossing next to the main library. The Science Building is right after the pedestrian crossing; the entrances are in the middle of the building on either side. The entrance to the Dept. of Theoretical Physics is at the ground floor of the main lobby.
Take bus 66 or 67A from Pearse Street/Westmoreland Street/South Quays. There are several (2-4) buses per hour; journey time approx. 1 hour. For Dublin Bus timetables see the Dublin Bus website.
Get off the 66 bus at Maynooth Main Street (Kilcock buses continue to the Northern Campus and stop next to the pedestrian crossing, see above), go to the old (Southern) campus gate, then follow the directions given above. With 67A bus, get off at the final stop opposite the Glenroyal Hotel, walk to the Main Street (traffic lights), then turn left to the old (Southern) campus gate.
Follow M4 all the way to Maynooth exit (signposted), turn right at the roundabout (4th exit), cross the bridge over the motorway, then follow the street (Straffan Rd.) until it ends at a T-junction with the Main St. Following the signposts to the North Campus, turn left at the traffic lights, then right at the next traffic lights. Immediately after the new Dunnes Stores, turn left (traffic lights) and continue through the next traffic lights and past the pedestrian crossing to the roundabout. The main entrance to the North Campus is on the right (the third exit of the roundabout). Turn left onto the campus ring road and continue along the ring road until you are almost back where you started; the Science Building is immediately on your right as you pass the main pedestrian axis. Driving time from the Quays is about 30 mins. in ideal conditions, but slower in afternoons (in particular on Fridays).
Please note that car parking at the university is very restricted, and most parking is permit only during term time. Pay and display car parks for visitors are located at the rear of the Callan Building and on the ring road near the student residences and playing fields. It may also be possible to obtain a visitor's permit; contact the department in advance if you require this.
For more information about car parking, see the Traffic Management web pages.