From the Autostrada A1 take the Tangenziale Est and exit at Salario-Centro; continue on Salaria for about 7 km, then exit at Conca D'Oro/Prati Fiscali. This will take you directly to Via dei Prati Fiscali.
The hotel is only 5 km from Termini station and you can get here via bus no. 38 (toward Baseggio) from Piazza dei Cinquecento in front of the station, taking it to the Valle Melaina-Ventotene stop which is 200 m from the hotel.
From the bus stop, walk toward Piazzale Jonio (100 m), turn right on Via dei Prati Fiscali and after 100 m you will see Hotel La Pergola across the street.
You can reach the hotel from the Fiumicino airport:
By taking the Leonardo Express train to Termini station, then taking the bus as per the directions above;
By taking the FR1 train to the Nomentana stop, then taking bus no. 84 (toward Baseggio) and getting out at the Pantelleria stop.
From that stop, walk 200 m along Viale Jonio to Piazzale Jonio, then continue on to Via dei Prati Fiscali. After 100 m you will see Hotel La Pergola across the street.
From the Ciampino airport you can reach the hotel by taking the Cotral bus to the Anagnina stop on the Metro A line, then continue on the Metro to Termini station. Take the bus from here, following the directions above.