たものだ: looking back on things one used to do
Recall past habits or scenes with たものだ. Distinguish experience, a single event, and whether the same habit continues today.
Remembering a repeated scene from the past
学生のころは、夜遅くまで本を読んだものです。 recalls how the speaker used to read late into the night as a student. It looks back on a repeated pattern rather than a single day's completed reading.
Add ものだ to the ta-form. 夏休みには祖母の家へ行ったものです。 recalls visiting one's grandmother during summer vacations without specifying the exact number of visits.
Experience versus a single event
祖母の家へ行ったことがあります。 states that someone has visited their grandmother's home before. 行ったものです instead centers on looking back at a repeated past pattern, unlike a simple answer about whether an experience exists.
昨日、図書館へ行きました。 reports one visit to the library yesterday. Do not add たものだ simply because something is in the past; check for a habit or period to look back on.
The present situation needs separate confirmation
昔はこの道をよく歩いたものです。 recalls often walking this road in the past. It does not logically establish that the speaker never walks it now, so the current habit can be asked about separately.
The final です politely conveys the recollection. Although ものです has a nonpast ending, 歩いた and 昔 place the remembered activity in the past; do not turn it into a present habit.
Quick check: Does 若いころは毎週泳いだものです。 mean swimming once in one's lifetime?
Show the answer and why
No. It recalls a habit of swimming every week when young. Read the frequency 毎週 together with the recollection expressed by たものだ.