To get to Harrow by car, you can take the A40 or the M1 and exit at junction 4. From central London, take the A40 or the A406. The drive should take around 30-40 minutes depending on traffic.
By rail, Harrow has several stations including Harrow-on-the-Hill, Harrow & Wealdstone and North Harrow. Trains run to these stations from London Euston, Watford Junction and other surrounding areas.
If you're coming from nearby landmarks, you can take the Metropolitan line from Wembley Park or Watford, or the Bakerloo line from Paddington. Alternatively, you can take a bus from nearby towns such as Ruislip, Pinner or Edgware.
To avoid traffic, it's best to avoid driving during peak hours. Public transportation can be a good option as there are frequent trains and buses to Harrow. If you're driving, there are several car parks in Harrow town centre that offer affordable parking.
The closest airport to Harrow is London Heathrow Airport, which is approximately 10 miles away. The suggested route from Heathrow to Harrow is via the M4 motorway and then onto the A312. Alternatively, one can take the Piccadilly line on the London Underground from Heathrow to Harrow-on-the-Hill station.